diff --git a/dev-packages/e2e-tests/test-applications/solidstart-2/package.json b/dev-packages/e2e-tests/test-applications/solidstart-2/package.json
index 9fd694db92d4..04b5c40c783a 100644
--- a/dev-packages/e2e-tests/test-applications/solidstart-2/package.json
+++ b/dev-packages/e2e-tests/test-applications/solidstart-2/package.json
@@ -9,7 +9,10 @@
     "start": "HOST=localhost PORT=3030 node .output/server/index.mjs",
     "test:prod": "TEST_ENV=production playwright test",
     "test:build": "pnpm install && pnpm build",
-    "test:assert": "pnpm test:prod"
+    "test:assert": "pnpm test:prod",
+    "test:build:tunnel": "pnpm install && E2E_TEST_TUNNEL=1 pnpm build",
+    "test:assert:tunnel": "E2E_TEST_TUNNEL=1 E2E_TEST_DSN=http://public@localhost:3031/1337 TEST_ENV=production playwright test tunnel",
+    "test:assert:tunnel-dev": "E2E_TEST_TUNNEL=1 E2E_TEST_DSN=http://public@localhost:3031/1337 TEST_ENV=development playwright test tunnel"
   },
   "type": "module",
   "dependencies": {
@@ -38,6 +41,18 @@
     "node": ">=24"
   },
   "sentryTest": {
-    "optional": true
+    "optional": true,
+    "variants": [
+      {
+        "build-command": "pnpm test:build:tunnel",
+        "assert-command": "pnpm test:assert:tunnel",
+        "label": "solidstart-2 (tunnel)"
+      },
+      {
+        "label": "solidstart-2 (tunnel-dev)",
+        "build-command": "pnpm install",
+        "assert-command": "pnpm test:assert:tunnel-dev"
+      }
+    ]
   }
 }
diff --git a/dev-packages/e2e-tests/test-applications/solidstart-2/playwright.config.mjs b/dev-packages/e2e-tests/test-applications/solidstart-2/playwright.config.mjs
index b52ff06a5105..2d40cab81f7e 100644
--- a/dev-packages/e2e-tests/test-applications/solidstart-2/playwright.config.mjs
+++ b/dev-packages/e2e-tests/test-applications/solidstart-2/playwright.config.mjs
@@ -1,7 +1,7 @@
 import { getPlaywrightConfig } from '@sentry-internal/test-utils';
 
 const config = getPlaywrightConfig({
-  startCommand: 'pnpm start',
+  startCommand: process.env.TEST_ENV === 'development' ? 'pnpm exec vite dev --port 3030' : 'pnpm start',
   port: 3030,
 });
 
diff --git a/dev-packages/e2e-tests/test-applications/solidstart-2/server/plugins/sentry.ts b/dev-packages/e2e-tests/test-applications/solidstart-2/server/plugins/sentry.ts
index 812abe8255fb..b28336bff817 100644
--- a/dev-packages/e2e-tests/test-applications/solidstart-2/server/plugins/sentry.ts
+++ b/dev-packages/e2e-tests/test-applications/solidstart-2/server/plugins/sentry.ts
@@ -7,7 +7,7 @@ export default definePlugin(() => {
     dsn: process.env.E2E_TEST_DSN,
     environment: 'qa', // dynamic sampling bias to keep transactions
     tracesSampleRate: 1.0, //  Capture 100% of the transactions
-    tunnel: 'http://localhost:3031/', // proxy server
+    tunnel: process.env.E2E_TEST_TUNNEL ? true : 'http://localhost:3031/', // proxy server
     debug: !!process.env.DEBUG,
   });
 });
diff --git a/dev-packages/e2e-tests/test-applications/solidstart-2/src/entry-client.tsx b/dev-packages/e2e-tests/test-applications/solidstart-2/src/entry-client.tsx
index 11087fbb5918..ce51cefc79f3 100644
--- a/dev-packages/e2e-tests/test-applications/solidstart-2/src/entry-client.tsx
+++ b/dev-packages/e2e-tests/test-applications/solidstart-2/src/entry-client.tsx
@@ -3,13 +3,16 @@ import * as Sentry from '@sentry/solidstart';
 import { solidRouterBrowserTracingIntegration } from '@sentry/solidstart/solidrouter';
 import { StartClient, mount } from '@solidjs/start/client';
 
+declare const __E2E_TEST_TUNNEL__: boolean;
+
 Sentry.init({
   // We can't use env variables here, seems like they are stripped
   // out in production builds.
-  dsn: 'https://public@dsn.ingest.sentry.io/1337',
+  // The tunnel variant forwards to the test proxy, so the DSN has to point there.
+  dsn: __E2E_TEST_TUNNEL__ ? 'http://public@localhost:3031/1337' : 'https://public@dsn.ingest.sentry.io/1337',
   environment: 'qa', // dynamic sampling bias to keep transactions
   integrations: [solidRouterBrowserTracingIntegration()],
-  tunnel: 'http://localhost:3031/', // proxy server
+  tunnel: __E2E_TEST_TUNNEL__ ? true : 'http://localhost:3031/', // proxy server
   // Performance Monitoring
   tracesSampleRate: 1.0, //  Capture 100% of the transactions
   debug: !!import.meta.env.DEBUG,
diff --git a/dev-packages/e2e-tests/test-applications/solidstart-2/tests/tunnel.test.ts b/dev-packages/e2e-tests/test-applications/solidstart-2/tests/tunnel.test.ts
new file mode 100644
index 000000000000..92b0892e5925
--- /dev/null
+++ b/dev-packages/e2e-tests/test-applications/solidstart-2/tests/tunnel.test.ts
@@ -0,0 +1,37 @@
+import { expect, test } from '@playwright/test';
+import { getSpanOp, waitForStreamedSpan } from '@sentry-internal/test-utils';
+
+test.skip(!process.env.E2E_TEST_TUNNEL, 'Only runs in the tunnel variant');
+
+const APP_NAME = 'solidstart-2';
+const TUNNEL_PATH = /^\/[a-z0-9]{1,7}$/;
+
+test('answers the managed tunnel and drops its server span', async ({ page }) => {
+  const tunnelServerSpanPromise = waitForStreamedSpan(
+    APP_NAME,
+    span => getSpanOp(span) === 'http.server' && TUNNEL_PATH.test(String(span.attributes['url.path']?.value ?? '')),
+  );
+  const tunnelResponsePromise = page.waitForResponse(
+    response => response.request().method() === 'POST' && TUNNEL_PATH.test(new URL(response.url()).pathname),
+  );
+
+  await page.goto('/');
+  const tunnelResponse = await tunnelResponsePromise;
+
+  expect(tunnelResponse.status()).toBe(200);
+  expect(new URL(tunnelResponse.url()).origin).toBe(new URL(page.url()).origin);
+
+  // Anchor on a regular server span requested after the tunnel traffic: spans flush in order, so a tunnel span
+  // would arrive first.
+  const anchorSpanPromise = waitForStreamedSpan(
+    APP_NAME,
+    span => getSpanOp(span) === 'http.server' && String(span.attributes['url.path']?.value ?? '') === '/users/6',
+  );
+  await page.request.get('/users/6');
+
+  const winner = await Promise.race([
+    tunnelServerSpanPromise.then(() => 'tunnel' as const),
+    anchorSpanPromise.then(() => 'anchor' as const),
+  ]);
+  expect(winner).toBe('anchor');
+});
diff --git a/dev-packages/e2e-tests/test-applications/solidstart-2/vite.config.ts b/dev-packages/e2e-tests/test-applications/solidstart-2/vite.config.ts
index d3ffd97997a9..28c43c71e6e1 100644
--- a/dev-packages/e2e-tests/test-applications/solidstart-2/vite.config.ts
+++ b/dev-packages/e2e-tests/test-applications/solidstart-2/vite.config.ts
@@ -4,6 +4,9 @@ import { nitro } from 'nitro/vite';
 import { defineConfig } from 'vite';
 
 export default defineConfig({
+  define: {
+    __E2E_TEST_TUNNEL__: JSON.stringify(!!process.env.E2E_TEST_TUNNEL),
+  },
   plugins: [
     solidStart({
       appRoot: './src',
diff --git a/dev-packages/e2e-tests/test-applications/solidstart/app.config.ts b/dev-packages/e2e-tests/test-applications/solidstart/app.config.ts
index 71061cf25d96..7486f6ecf58c 100644
--- a/dev-packages/e2e-tests/test-applications/solidstart/app.config.ts
+++ b/dev-packages/e2e-tests/test-applications/solidstart/app.config.ts
@@ -4,5 +4,12 @@ import { defineConfig } from '@solidjs/start/config';
 export default defineConfig(
   withSentry({
     middleware: './src/middleware.ts',
+    // The base-path variant serves the app, and so the tunnel, under `/app`.
+    ...(process.env.E2E_TEST_BASE_PATH && { server: { baseURL: `${process.env.E2E_TEST_BASE_PATH}/` } }),
+    vite: {
+      define: {
+        __E2E_TEST_TUNNEL__: JSON.stringify(!!process.env.E2E_TEST_TUNNEL),
+      },
+    },
   }),
 );
diff --git a/dev-packages/e2e-tests/test-applications/solidstart/instrument.server.mjs b/dev-packages/e2e-tests/test-applications/solidstart/instrument.server.mjs
index f75de066068a..c543b273ad5d 100644
--- a/dev-packages/e2e-tests/test-applications/solidstart/instrument.server.mjs
+++ b/dev-packages/e2e-tests/test-applications/solidstart/instrument.server.mjs
@@ -6,6 +6,6 @@ Sentry.init({
   dsn: process.env.E2E_TEST_DSN,
   environment: 'qa', // dynamic sampling bias to keep transactions
   tracesSampleRate: 1.0, //  Capture 100% of the transactions
-  tunnel: 'http://localhost:3031/', // proxy server
+  tunnel: process.env.E2E_TEST_TUNNEL ? true : 'http://localhost:3031/', // proxy server
   debug: !!process.env.DEBUG,
 });
diff --git a/dev-packages/e2e-tests/test-applications/solidstart/package.json b/dev-packages/e2e-tests/test-applications/solidstart/package.json
index ac2b8c393432..118efe66bc77 100644
--- a/dev-packages/e2e-tests/test-applications/solidstart/package.json
+++ b/dev-packages/e2e-tests/test-applications/solidstart/package.json
@@ -10,7 +10,13 @@
     "test:prod": "TEST_ENV=production playwright test",
     "test:build": "pnpm install && pnpm build",
     "test:assert": "pnpm test:prod && pnpm test:dev",
-    "test:dev": "TEST_ENV=development playwright test db"
+    "test:dev": "TEST_ENV=development playwright test db",
+    "test:build:tunnel": "pnpm install && E2E_TEST_TUNNEL=1 pnpm build",
+    "test:build:tunnel-basepath": "pnpm install && E2E_TEST_TUNNEL=1 E2E_TEST_BASE_PATH=/app pnpm build",
+    "test:assert:tunnel": "E2E_TEST_TUNNEL=1 E2E_TEST_DSN=http://public@localhost:3031/1337 TEST_ENV=production playwright test tunnel",
+    "test:assert:tunnel-basepath": "E2E_TEST_TUNNEL=1 E2E_TEST_BASE_PATH=/app E2E_TEST_DSN=http://public@localhost:3031/1337 TEST_ENV=production playwright test tunnel",
+    "test:assert:tunnel-dev": "E2E_TEST_TUNNEL=1 E2E_TEST_DSN=http://public@localhost:3031/1337 TEST_ENV=development playwright test tunnel",
+    "test:assert:tunnel-basepath-dev": "E2E_TEST_TUNNEL=1 E2E_TEST_BASE_PATH=/app E2E_TEST_DSN=http://public@localhost:3031/1337 TEST_ENV=development playwright test tunnel"
   },
   "type": "module",
   "dependencies": {
@@ -30,11 +36,35 @@
     "jsdom": "^24.0.0",
     "solid-js": "1.9.5",
     "typescript": "^5.4.5",
-    "vinxi": "^0.4.0",
-    "vite": "^5.4.11",
+    "vinxi": "^0.5.11",
+    "vite": "^6.4.4",
     "vite-plugin-solid": "^2.11.6"
   },
   "volta": {
     "extends": "../../package.json"
+  },
+  "sentryTest": {
+    "variants": [
+      {
+        "build-command": "pnpm test:build:tunnel",
+        "assert-command": "pnpm test:assert:tunnel",
+        "label": "solidstart (tunnel)"
+      },
+      {
+        "build-command": "pnpm test:build:tunnel-basepath",
+        "assert-command": "pnpm test:assert:tunnel-basepath",
+        "label": "solidstart (tunnel-basepath)"
+      },
+      {
+        "build-command": "pnpm install",
+        "assert-command": "pnpm test:assert:tunnel-dev",
+        "label": "solidstart (tunnel-dev)"
+      },
+      {
+        "build-command": "pnpm install",
+        "assert-command": "pnpm test:assert:tunnel-basepath-dev",
+        "label": "solidstart (tunnel-basepath-dev)"
+      }
+    ]
   }
 }
diff --git a/dev-packages/e2e-tests/test-applications/solidstart/src/entry-client.tsx b/dev-packages/e2e-tests/test-applications/solidstart/src/entry-client.tsx
index 11087fbb5918..a92e54089aed 100644
--- a/dev-packages/e2e-tests/test-applications/solidstart/src/entry-client.tsx
+++ b/dev-packages/e2e-tests/test-applications/solidstart/src/entry-client.tsx
@@ -3,13 +3,15 @@ import * as Sentry from '@sentry/solidstart';
 import { solidRouterBrowserTracingIntegration } from '@sentry/solidstart/solidrouter';
 import { StartClient, mount } from '@solidjs/start/client';
 
+declare const __E2E_TEST_TUNNEL__: boolean;
+
 Sentry.init({
   // We can't use env variables here, seems like they are stripped
   // out in production builds.
-  dsn: 'https://public@dsn.ingest.sentry.io/1337',
+  dsn: __E2E_TEST_TUNNEL__ ? 'http://public@localhost:3031/1337' : 'https://public@dsn.ingest.sentry.io/1337',
   environment: 'qa', // dynamic sampling bias to keep transactions
   integrations: [solidRouterBrowserTracingIntegration()],
-  tunnel: 'http://localhost:3031/', // proxy server
+  tunnel: __E2E_TEST_TUNNEL__ ? true : 'http://localhost:3031/', // proxy server
   // Performance Monitoring
   tracesSampleRate: 1.0, //  Capture 100% of the transactions
   debug: !!import.meta.env.DEBUG,
diff --git a/dev-packages/e2e-tests/test-applications/solidstart/src/instrument.server.ts b/dev-packages/e2e-tests/test-applications/solidstart/src/instrument.server.ts
index 3dd5d8933b7b..1e1ef4a28d61 100644
--- a/dev-packages/e2e-tests/test-applications/solidstart/src/instrument.server.ts
+++ b/dev-packages/e2e-tests/test-applications/solidstart/src/instrument.server.ts
@@ -4,6 +4,6 @@ Sentry.init({
   dsn: process.env.E2E_TEST_DSN,
   environment: 'qa', // dynamic sampling bias to keep transactions
   tracesSampleRate: 1.0, //  Capture 100% of the transactions
-  tunnel: 'http://localhost:3031/', // proxy server
+  tunnel: process.env.E2E_TEST_TUNNEL ? true : 'http://localhost:3031/', // proxy server
   debug: !!process.env.DEBUG,
 });
diff --git a/dev-packages/e2e-tests/test-applications/solidstart/src/middleware.ts b/dev-packages/e2e-tests/test-applications/solidstart/src/middleware.ts
index 88123a035fb6..9dee5a5d3eb8 100644
--- a/dev-packages/e2e-tests/test-applications/solidstart/src/middleware.ts
+++ b/dev-packages/e2e-tests/test-applications/solidstart/src/middleware.ts
@@ -2,5 +2,14 @@ import { sentryBeforeResponseMiddleware } from '@sentry/solidstart';
 import { createMiddleware } from '@solidjs/start/middleware';
 
 export default createMiddleware({
+  onRequest: [
+    // The tunnel variant checks that the managed tunnel answers before an auth middleware like this one.
+    event => {
+      const request = event.request;
+      if (process.env.E2E_TEST_TUNNEL && request.method === 'POST' && request.headers.get('x-auth') !== 'ok') {
+        return new Response('blocked by user auth', { status: 401 });
+      }
+    },
+  ],
   onBeforeResponse: [sentryBeforeResponseMiddleware()],
 });
diff --git a/dev-packages/e2e-tests/test-applications/solidstart/tests/tunnel.test.ts b/dev-packages/e2e-tests/test-applications/solidstart/tests/tunnel.test.ts
new file mode 100644
index 000000000000..3ff1081fff07
--- /dev/null
+++ b/dev-packages/e2e-tests/test-applications/solidstart/tests/tunnel.test.ts
@@ -0,0 +1,42 @@
+import { expect, test } from '@playwright/test';
+import { getSpanOp, waitForStreamedSpan } from '@sentry-internal/test-utils';
+
+test.skip(!process.env.E2E_TEST_TUNNEL, 'Only runs in the tunnel variant');
+
+const APP_NAME = 'solidstart';
+const BASE_PATH = process.env.E2E_TEST_BASE_PATH ?? '';
+const TUNNEL_PATH = new RegExp(`^${BASE_PATH}/[a-z0-9]{1,7}$`);
+
+test('answers the managed tunnel before the app middleware', async ({ page }) => {
+  // The variant's auth middleware rejects every other POST.
+  expect((await page.request.post(`${BASE_PATH}/`, { data: 'x' })).status()).toBe(401);
+
+  const tunnelServerSpanPromise = waitForStreamedSpan(
+    APP_NAME,
+    span => getSpanOp(span) === 'http.server' && TUNNEL_PATH.test(String(span.attributes['url.path']?.value ?? '')),
+  );
+  const tunnelResponsePromise = page.waitForResponse(
+    response => response.request().method() === 'POST' && TUNNEL_PATH.test(new URL(response.url()).pathname),
+  );
+
+  await page.goto(`${BASE_PATH}/`);
+  const tunnelResponse = await tunnelResponsePromise;
+
+  expect(tunnelResponse.status()).toBe(200);
+  expect(new URL(tunnelResponse.url()).origin).toBe(new URL(page.url()).origin);
+
+  // Anchor on a regular server span requested after the tunnel traffic: spans flush in order, so a tunnel span
+  // would arrive first.
+  const anchorSpanPromise = waitForStreamedSpan(
+    APP_NAME,
+    span =>
+      getSpanOp(span) === 'http.server' && String(span.attributes['url.path']?.value ?? '') === `${BASE_PATH}/users/6`,
+  );
+  await page.request.get(`${BASE_PATH}/users/6`);
+
+  const winner = await Promise.race([
+    tunnelServerSpanPromise.then(() => 'tunnel' as const),
+    anchorSpanPromise.then(() => 'anchor' as const),
+  ]);
+  expect(winner).toBe('anchor');
+});
diff --git a/packages/solidstart/rollup.npm.config.mjs b/packages/solidstart/rollup.npm.config.mjs
index d28b29896b10..9b296fb352ae 100644
--- a/packages/solidstart/rollup.npm.config.mjs
+++ b/packages/solidstart/rollup.npm.config.mjs
@@ -13,6 +13,7 @@ export default makeNPMConfigVariants(
       'src/client/solidrouter.ts',
       'src/server/solidrouter.ts',
       'src/vite/index.ts',
+      'src/nitro/tunnelPlugin.ts',
     ],
     // prevent this internal code from ending up in our built package (this doesn't happen automatically because
     // the name doesn't match an SDK dependency)
diff --git a/packages/solidstart/src/client/sdk.ts b/packages/solidstart/src/client/sdk.ts
index 06ee8f092094..7473f329d11c 100644
--- a/packages/solidstart/src/client/sdk.ts
+++ b/packages/solidstart/src/client/sdk.ts
@@ -1,6 +1,7 @@
 import type { Client, Integration } from '@sentry/core';
 import { applySdkMetadata } from '@sentry/core';
 import type { BrowserOptions } from '@sentry/solid';
+import { applyTunnelBasePath } from '../common/tunnel';
 import {
   browserTracingIntegration,
   getDefaultIntegrations as getDefaultSolidIntegrations,
@@ -19,6 +20,7 @@ export function init(options: BrowserOptions): Client | undefined {
     ...options,
   };
 
+  applyTunnelBasePath(opts);
   applySdkMetadata(opts, 'solidstart', ['solidstart', 'solid']);
 
   return initSolidSDK(opts);
diff --git a/packages/solidstart/src/common/tunnel.ts b/packages/solidstart/src/common/tunnel.ts
new file mode 100644
index 000000000000..09fbf034b1eb
--- /dev/null
+++ b/packages/solidstart/src/common/tunnel.ts
@@ -0,0 +1,17 @@
+import type { Options } from '@sentry/core';
+import { applyTunnelDefaults } from '@sentry/core';
+
+/** Set on the server by `withSentry` to the app's `server.baseURL`. */
+export const TUNNEL_BASE_PATH_GLOBAL = '__sentry_solidstart_base_path';
+
+declare const __SENTRY_SOLIDSTART_TUNNEL_BASE_PATH__: string | undefined;
+
+/**
+ * Serves the browser's managed tunnel under the app's `server.baseURL`, which `withSentry` defines at build time.
+ * A `basePath` the user set wins.
+ */
+export function applyTunnelBasePath(options: Pick<Options, 'tunnel'>): void {
+  const basePath =
+    typeof __SENTRY_SOLIDSTART_TUNNEL_BASE_PATH__ !== 'undefined' ? __SENTRY_SOLIDSTART_TUNNEL_BASE_PATH__ : '';
+  options.tunnel = applyTunnelDefaults(options.tunnel, basePath ? { basePath } : undefined);
+}
diff --git a/packages/solidstart/src/config/types.ts b/packages/solidstart/src/config/types.ts
index 14e814c78195..d9c13ae76ebb 100644
--- a/packages/solidstart/src/config/types.ts
+++ b/packages/solidstart/src/config/types.ts
@@ -9,6 +9,7 @@ export type RollupConfig = {
 export type SolidStartInlineConfig = NonNullable<Parameters<typeof defineConfig>[0]>;
 
 export type SolidStartInlineServerConfig = {
+  plugins?: string[];
   hooks?: {
     close?: () => unknown;
     'rollup:before'?: (nitro: Nitro) => unknown;
diff --git a/packages/solidstart/src/config/withSentry.ts b/packages/solidstart/src/config/withSentry.ts
index e4b0f6d08b49..973bf6c78666 100644
--- a/packages/solidstart/src/config/withSentry.ts
+++ b/packages/solidstart/src/config/withSentry.ts
@@ -1,4 +1,5 @@
-import { debug } from '@sentry/core';
+import { fileURLToPath } from 'node:url';
+import { debug, GLOBAL_OBJ, normalizeTunnelBasePath } from '@sentry/core';
 import { INSTRUMENTED_MODULE_NAMES } from '@sentry/server-utils/orchestrion/config';
 import {
   commonJSInteropOptions,
@@ -6,6 +7,7 @@ import {
   sentryOrchestrionPlugin,
 } from '@sentry/server-utils/orchestrion/rollup';
 import type { Nitro, NitroConfig } from 'nitropack';
+import { TUNNEL_BASE_PATH_GLOBAL } from '../common/tunnel';
 import { addSentryPluginToVite } from '../vite/sentrySolidStartVite';
 import type { SentrySolidStartPluginOptions } from '../vite/types';
 import {
@@ -46,11 +48,21 @@ export function withSentry(
   };
 
   const server = (solidStartConfig.server || {}) as SolidStartInlineServerConfig;
+  // Requests reach the tunnel with `server.baseURL` still in front, so both sides serve it under that.
+  const tunnelBasePath = normalizeTunnelBasePath(
+    (server as SolidStartInlineServerConfig & { baseURL?: string }).baseURL,
+  );
+  // vinxi's dev server runs Nitro in this process, so the tunnel plugin can read it from here in dev.
+  if (tunnelBasePath) {
+    (GLOBAL_OBJ as { [TUNNEL_BASE_PATH_GLOBAL]?: string })[TUNNEL_BASE_PATH_GLOBAL] = tunnelBasePath;
+  }
+
   const viteConfig = solidStartConfig.vite;
   const vite =
     typeof viteConfig === 'function'
-      ? (...args: Parameters<typeof viteConfig>) => addSentryPluginToVite(viteConfig(...args), sentryPluginOptions)
-      : addSentryPluginToVite(viteConfig, sentryPluginOptions);
+      ? (...args: Parameters<typeof viteConfig>) =>
+          addSentryPluginToVite(viteConfig(...args), sentryPluginOptions, tunnelBasePath)
+      : addSentryPluginToVite(viteConfig, sentryPluginOptions, tunnelBasePath);
 
   const addBuildTimeInstrumentation = sentryPluginOptions.buildTimeInstrumentation !== false;
 
@@ -61,6 +73,14 @@ export function withSentry(
       // but at runtime it holds resolved plugin objects we can push onto, so narrow to our own shape.
       const sentryRollupConfig = rollupConfig as unknown as RollupConfig;
 
+      if (tunnelBasePath) {
+        // The built server runs in another process, so the tunnel plugin reads the base path from the bundle.
+        sentryRollupConfig.plugins.push({
+          name: 'sentry-solidstart-tunnel-base-path',
+          banner: `globalThis.${TUNNEL_BASE_PATH_GLOBAL} = ${JSON.stringify(tunnelBasePath)};`,
+        });
+      }
+
       if (addBuildTimeInstrumentation) {
         sentryRollupConfig.plugins.push(
           sentryOrchestrionPlugin({ buildTimeInstrumentation: sentryPluginOptions.buildTimeInstrumentation }),
@@ -116,6 +136,15 @@ export function withSentry(
       externals,
       commonJS,
       modules: [...existingModules, sentryNitroModule],
+      // Through `server.plugins`, since vinxi's dev server ignores plugins that Nitro modules add.
+      plugins: [...(server.plugins || []), getTunnelPluginPath()],
     },
   };
 }
+
+function getTunnelPluginPath(): string {
+  const url = new URL('../nitro/tunnelPlugin.js', import.meta.url);
+
+  // `import.meta.url` is a file URL in the built package, but not in every test environment.
+  return url.protocol === 'file:' ? fileURLToPath(url) : url.pathname;
+}
diff --git a/packages/solidstart/src/nitro/tunnelPlugin.ts b/packages/solidstart/src/nitro/tunnelPlugin.ts
new file mode 100644
index 000000000000..edb892a5fcdc
--- /dev/null
+++ b/packages/solidstart/src/nitro/tunnelPlugin.ts
@@ -0,0 +1,60 @@
+import { Readable } from 'node:stream';
+import {
+  getClient,
+  GLOBAL_OBJ,
+  handleTunnelRequestIfMatched,
+  isTunnelRequest,
+  setManagedTunnelBasePath,
+} from '@sentry/core';
+import type { NitroAppPlugin } from 'nitropack';
+import { TUNNEL_BASE_PATH_GLOBAL } from '../common/tunnel';
+
+/**
+ * Answers managed tunnel requests on SolidStart v1 (Nitro v2). The `request` hook runs before the app's middleware
+ * and routing. `withSentry` registers it.
+ */
+export default (nitroApp => {
+  // The hook sees the path before Nitro strips `server.baseURL`, so the tunnel is served under it. `init` may run
+  // after this plugin, so this is repeated for the first requests after it too.
+  const applyBaseURL = (): void =>
+    setManagedTunnelBasePath(
+      getClient(),
+      (GLOBAL_OBJ as { [TUNNEL_BASE_PATH_GLOBAL]?: string })[TUNNEL_BASE_PATH_GLOBAL],
+    );
+  applyBaseURL();
+
+  nitroApp.hooks.hook('request', async event => {
+    applyBaseURL();
+
+    const { req, res } = event.node;
+    // Checked on the method and path first, so no other request's body gets wrapped in a web `Request`.
+    if (!isTunnelRequest(req)) {
+      return;
+    }
+
+    const headers = new Headers();
+    for (const [name, value] of Object.entries(req.headers)) {
+      if (value !== undefined) {
+        headers.set(name, Array.isArray(value) ? value.join(', ') : value);
+      }
+    }
+
+    const tunnelResponse = await handleTunnelRequestIfMatched(
+      new Request(`http://${req.headers.host}${req.url}`, {
+        method: req.method,
+        headers,
+        body: Readable.toWeb(req) as ReadableStream,
+        // Required by Node's `fetch` for a streamed body.
+        duplex: 'half',
+      } as RequestInit),
+    );
+    if (!tunnelResponse) {
+      return;
+    }
+
+    // Writing the response marks the event as handled, so Nitro stops here.
+    res.statusCode = tunnelResponse.status;
+    tunnelResponse.headers.forEach((value, name) => res.setHeader(name, value));
+    res.end(Buffer.from(await tunnelResponse.arrayBuffer()));
+  });
+}) satisfies NitroAppPlugin;
diff --git a/packages/solidstart/src/vite/sentrySolidStartVite.ts b/packages/solidstart/src/vite/sentrySolidStartVite.ts
index 8bb0a55741d1..61b884c29d2e 100644
--- a/packages/solidstart/src/vite/sentrySolidStartVite.ts
+++ b/packages/solidstart/src/vite/sentrySolidStartVite.ts
@@ -7,10 +7,22 @@ import type { SentrySolidStartPluginOptions } from './types';
 /**
  * Various Sentry vite plugins to be used for SolidStart.
  */
-export const sentrySolidStartVite = (options: SentrySolidStartPluginOptions = {}, viteConfig: UserConfig): Plugin[] => {
+export const sentrySolidStartVite = (
+  options: SentrySolidStartPluginOptions = {},
+  viteConfig: UserConfig,
+  tunnelBasePath = '',
+): Plugin[] => {
   warnOnRemovedBuildOptions(options, ['unstable_sentryVitePluginOptions']);
 
-  const sentryPlugins: Plugin[] = [];
+  const sentryPlugins: Plugin[] = [
+    {
+      name: 'sentry-solidstart-tunnel-base-path',
+      // Serves the browser's managed tunnel under `server.baseURL`, like every other route of the app.
+      config: () => ({
+        define: { __SENTRY_SOLIDSTART_TUNNEL_BASE_PATH__: JSON.stringify(tunnelBasePath) },
+      }),
+    },
+  ];
 
   if (options.autoInjectServerSentry !== 'experimental_dynamic-import') {
     sentryPlugins.push(makeBuildInstrumentationFilePlugin(options));
@@ -31,9 +43,13 @@ export const sentrySolidStartVite = (options: SentrySolidStartPluginOptions = {}
 /**
  * Helper to add the Sentry SolidStart vite plugin to a vite config.
  */
-export const addSentryPluginToVite = (config: UserConfig = {}, options: SentrySolidStartPluginOptions): UserConfig => {
+export const addSentryPluginToVite = (
+  config: UserConfig = {},
+  options: SentrySolidStartPluginOptions,
+  tunnelBasePath?: string,
+): UserConfig => {
   const plugins = Array.isArray(config.plugins) ? [...config.plugins] : [];
-  plugins.unshift(sentrySolidStartVite(options, config));
+  plugins.unshift(sentrySolidStartVite(options, config, tunnelBasePath));
 
   return {
     ...config,
diff --git a/packages/solidstart/test/common/tunnel.test.ts b/packages/solidstart/test/common/tunnel.test.ts
new file mode 100644
index 000000000000..a3d7168b0958
--- /dev/null
+++ b/packages/solidstart/test/common/tunnel.test.ts
@@ -0,0 +1,28 @@
+import { afterEach, describe, expect, it, vi } from 'vitest';
+import { applyTunnelBasePath } from '../../src/common/tunnel';
+
+describe('applyTunnelBasePath', () => {
+  afterEach(() => {
+    vi.unstubAllGlobals();
+  });
+
+  it('serves the managed tunnel under the defined base path, unless the user set one', () => {
+    vi.stubGlobal('__SENTRY_SOLIDSTART_TUNNEL_BASE_PATH__', '/app');
+    const managed: Parameters<typeof applyTunnelBasePath>[0] = { tunnel: true };
+    const own: Parameters<typeof applyTunnelBasePath>[0] = { tunnel: { basePath: '/custom' } };
+
+    applyTunnelBasePath(managed);
+    applyTunnelBasePath(own);
+
+    expect(managed.tunnel).toEqual({ basePath: '/app' });
+    expect(own.tunnel).toEqual({ basePath: '/custom' });
+  });
+
+  it('leaves the tunnel alone without a base path', () => {
+    const options: Parameters<typeof applyTunnelBasePath>[0] = { tunnel: true };
+
+    applyTunnelBasePath(options);
+
+    expect(options.tunnel).toBe(true);
+  });
+});
diff --git a/packages/solidstart/test/config/withSentry.test.ts b/packages/solidstart/test/config/withSentry.test.ts
index 3afba804811d..c4c056319b55 100644
--- a/packages/solidstart/test/config/withSentry.test.ts
+++ b/packages/solidstart/test/config/withSentry.test.ts
@@ -78,6 +78,16 @@ describe('withSentry()', () => {
     expect(addInstrumentationFileToBuildMock).toHaveBeenCalledWith(nitroOptions);
   });
 
+  it('registers the managed tunnel plugin through server.plugins and keeps user plugins', () => {
+    const config = withSentry({ server: { plugins: ['./user-plugin.ts'] } }, {});
+
+    expect((config?.server as { plugins?: string[] }).plugins).toEqual([
+      './user-plugin.ts',
+      // Vitest serves the source file, the built package the transpiled one.
+      expect.stringMatching(/\/nitro\/tunnelPlugin\.[jt]s$/),
+    ]);
+  });
+
   it('does not override user-defined hooks in server.hooks', () => {
     const config = withSentry(solidStartConfig, {});
     expect(config?.server.hooks?.['rollup:before']).toBe(userDefinedNitroRollupBeforeHookMock);
@@ -116,6 +126,7 @@ describe('withSentry()', () => {
     });
     const names = config?.vite.plugins.flat().map((plugin: Plugin) => plugin.name);
     expect(names).toEqual([
+      'sentry-solidstart-tunnel-base-path',
       'sentry-solidstart-build-instrumentation-file',
       'sentry-vite-plugin',
       'sentry-solidstart-update-source-map-setting',
@@ -139,6 +150,7 @@ describe('withSentry()', () => {
 
     const names = config?.vite.plugins.flat().map((plugin: Plugin) => plugin.name);
     expect(names).toEqual([
+      'sentry-solidstart-tunnel-base-path',
       'sentry-solidstart-build-instrumentation-file',
       'sentry-vite-plugin',
       'sentry-solidstart-update-source-map-setting',
@@ -166,6 +178,7 @@ describe('withSentry()', () => {
       .plugins.flat()
       .map((plugin: Plugin) => plugin.name);
     expect(names).toEqual([
+      'sentry-solidstart-tunnel-base-path',
       'sentry-solidstart-build-instrumentation-file',
       'sentry-vite-plugin',
       'sentry-solidstart-update-source-map-setting',
diff --git a/packages/solidstart/test/nitro/tunnelPlugin.test.ts b/packages/solidstart/test/nitro/tunnelPlugin.test.ts
new file mode 100644
index 000000000000..eac0ed370ce4
--- /dev/null
+++ b/packages/solidstart/test/nitro/tunnelPlugin.test.ts
@@ -0,0 +1,55 @@
+import { Readable } from 'node:stream';
+import type { Client } from '@sentry/core';
+import { createEnvelope, getCurrentScope, getTunnelPath, makeDsn, serializeEnvelope } from '@sentry/core';
+import { afterEach, describe, expect, it, vi } from 'vitest';
+import tunnelPlugin from '../../src/nitro/tunnelPlugin';
+
+const DSN = 'https://public@o1.ingest.sentry.io/1337';
+
+type RequestHook = (event: unknown) => Promise<void>;
+
+function setupPlugin(): RequestHook {
+  let requestHook: RequestHook | undefined;
+  (tunnelPlugin as (nitroApp: unknown) => void)({
+    hooks: { hook: (name: string, fn: RequestHook) => name === 'request' && (requestHook = fn) },
+  });
+
+  return requestHook!;
+}
+
+function makeEvent(method: string, url: string, body = ''): { event: unknown; res: { end: ReturnType<typeof vi.fn> } } {
+  const req = Object.assign(Readable.from([Buffer.from(body)]), { method, url, headers: { host: 'localhost' } });
+  const res = { statusCode: 200, setHeader: vi.fn(), end: vi.fn() };
+
+  return { event: { node: { req, res } }, res };
+}
+
+describe('SolidStart v1 tunnel plugin', () => {
+  afterEach(() => {
+    getCurrentScope().setClient(undefined);
+    vi.unstubAllGlobals();
+  });
+
+  it('answers tunnel requests from the request hook when `init` enabled the managed tunnel', async () => {
+    const options = { dsn: DSN, _managedTunnel: {} };
+    getCurrentScope().setClient({ getDsn: () => makeDsn(DSN), getOptions: () => options } as unknown as Client);
+    vi.stubGlobal(
+      'fetch',
+      vi.fn(() => Promise.resolve(new Response('forwarded'))),
+    );
+    const envelope = serializeEnvelope(createEnvelope({ dsn: DSN }, [])) as string;
+    const { event, res } = makeEvent('POST', getTunnelPath(DSN)!, envelope);
+
+    await setupPlugin()(event);
+
+    expect(res.end).toHaveBeenCalledWith(Buffer.from('forwarded'));
+  });
+
+  it('leaves every other request to the app', async () => {
+    const { event, res } = makeEvent('POST', '/api/users');
+
+    await setupPlugin()(event);
+
+    expect(res.end).not.toHaveBeenCalled();
+  });
+});
diff --git a/packages/solidstart/test/vite/sentrySolidStartVite.test.ts b/packages/solidstart/test/vite/sentrySolidStartVite.test.ts
index 545638f9e3dc..db2382efdc45 100644
--- a/packages/solidstart/test/vite/sentrySolidStartVite.test.ts
+++ b/packages/solidstart/test/vite/sentrySolidStartVite.test.ts
@@ -26,6 +26,7 @@ describe('sentrySolidStartVite()', () => {
     const plugins = getSentrySolidStartVitePlugins();
     const names = plugins.map(plugin => plugin.name);
     expect(names).toEqual([
+      'sentry-solidstart-tunnel-base-path',
       'sentry-solidstart-build-instrumentation-file',
       'sentry-vite-plugin',
       'sentry-solidstart-update-source-map-setting',
@@ -35,7 +36,7 @@ describe('sentrySolidStartVite()', () => {
   it("returns only build-instrumentation-file plugin if source maps upload isn't enabled", () => {
     const plugins = getSentrySolidStartVitePlugins({ sourcemaps: { disable: true } });
     const names = plugins.map(plugin => plugin.name);
-    expect(names).toEqual(['sentry-solidstart-build-instrumentation-file']);
+    expect(names).toEqual(['sentry-solidstart-tunnel-base-path', 'sentry-solidstart-build-instrumentation-file']);
   });
 
   it('returns only build-instrumentation-file plugin if `NODE_ENV` is development', async () => {
@@ -44,7 +45,7 @@ describe('sentrySolidStartVite()', () => {
 
     const plugins = getSentrySolidStartVitePlugins({ sourcemaps: { disable: false } });
     const names = plugins.map(plugin => plugin.name);
-    expect(names).toEqual(['sentry-solidstart-build-instrumentation-file']);
+    expect(names).toEqual(['sentry-solidstart-tunnel-base-path', 'sentry-solidstart-build-instrumentation-file']);
 
     process.env.NODE_ENV = previousEnv;
   });