diff --git a/src/frontend/src/components/LivePip.astro b/src/frontend/src/components/LivePip.astro
index 974e3a89b..8dedd57d7 100644
--- a/src/frontend/src/components/LivePip.astro
+++ b/src/frontend/src/components/LivePip.astro
@@ -320,6 +320,7 @@ import LiveSvg from '@assets/icons/live.svg';
 
     const doc = pipWindow.document;
     const iframe = doc.createElement('iframe');
+    iframe.referrerPolicy = 'strict-origin-when-cross-origin';
     iframe.src = embed.url;
     iframe.allow = embed.allow;
     iframe.setAttribute('aria-label', embed.label);
@@ -370,6 +371,10 @@ import LiveSvg from '@assets/icons/live.svg';
       width: 480,
       height: 270,
     });
+    // Give the initial about:blank document the opener's URL so embeds send a Referer.
+    // Do this before registering listeners: document.open() clears them.
+    pipWindow.document.open();
+    pipWindow.document.close();
     state.pipWindow = pipWindow;
     state.activeEmbedKey = '';
     pipWindow.addEventListener(
diff --git a/src/frontend/tests/e2e/live-pip.spec.ts b/src/frontend/tests/e2e/live-pip.spec.ts
new file mode 100644
index 000000000..451c4e819
--- /dev/null
+++ b/src/frontend/tests/e2e/live-pip.spec.ts
@@ -0,0 +1,105 @@
+import { expect, test, type Request } from '@playwright/test';
+import { dismissCookieConsentIfVisible } from '@tests/e2e/helpers';
+
+// Native Document PiP needs the full browser rather than headless shell.
+test.use({ channel: 'chromium' });
+
+for (const videoId of ['DtdP0JBawPI', null]) {
+  test(`native YouTube PiP sends a referrer for the ${videoId ? 'video' : 'channel fallback'}`, async ({
+    page,
+    context,
+    isMobile,
+  }) => {
+    test.skip(isMobile, 'Native Document Picture-in-Picture requires a desktop browser.');
+
+    const snapshot = {
+      isLive: true,
+      primarySource: 'twitch',
+      twitch: { live: true, channel: 'aspiredotdev' },
+      youtube: { live: true, videoId },
+      updatedAt: new Date().toISOString(),
+    };
+    await page.route(/\/api\/live\/?$/, (route) => route.fulfill({ json: snapshot }));
+    await page.route(/\/api\/live\/stream\/?$/, (route) =>
+      route.fulfill({
+        contentType: 'text/event-stream',
+        body: `event: state\ndata: ${JSON.stringify(snapshot)}\n\n`,
+      })
+    );
+
+    // Stub only the provider response, not PiP: Chromium must generate the real request.
+    const embeds: Request[] = [];
+    await context.route(
+      /^https:\/\/(?:www\.youtube-nocookie\.com\/embed\/|player\.twitch\.tv\/)/,
+      async (route) => {
+        embeds.push(route.request());
+        await route.fulfill({
+          contentType: 'text/html',
+          body: '<!doctype html><title>Provider player</title><p>Provider player</p>',
+        });
+      }
+    );
+
+    await page.goto('/');
+    await dismissCookieConsentIfVisible(page);
+    expect(await page.evaluate(() => 'documentPictureInPicture' in window)).toBe(true);
+    const expectedReferrer = new URL(page.url()).origin + '/';
+    const liveButton = () => page.locator('.live-btn:visible').first();
+    const menu = page.getByRole('dialog', { name: 'Choose how to watch' });
+    const youtube = menu.getByRole('button', { name: /Open YouTube Picture-in-Picture/ });
+    const twitch = menu.getByRole('button', { name: /Open Twitch Picture-in-Picture/ });
+
+    await expect(liveButton()).toHaveAttribute('data-source', 'both');
+    await liveButton().click();
+    const opened = context.waitForEvent('page');
+    await youtube.click();
+    const pip = await opened;
+
+    await expect.poll(() => embeds.length).toBe(1);
+    expect(await embeds[0].headerValue('referer')).toBe(expectedReferrer);
+    const embedUrl = new URL(embeds[0].url());
+    expect(embedUrl.origin).toBe('https://www.youtube-nocookie.com');
+    expect(embedUrl.pathname).toBe(`/embed/${videoId ?? 'live_stream'}`);
+    if (!videoId) {
+      expect(embedUrl.searchParams.get('channel')).toBe('UCW_UJkc7RhM_NPcDXnOCfrQ');
+    }
+    expect(embedUrl.searchParams.get('autoplay')).toBe('1');
+    expect(embedUrl.searchParams.get('mute')).toBe('1');
+    await expect(liveButton()).toHaveAttribute('data-pip-open', 'true');
+
+    await page.locator('header a[href="/docs/"]:visible').click();
+    await expect(page).toHaveURL(/\/docs\/$/);
+    await expect(liveButton()).toHaveAttribute('data-pip-open', 'true');
+    expect(pip.isClosed()).toBe(false);
+    await liveButton().click();
+    await youtube.click();
+    expect(embeds).toHaveLength(1);
+
+    await liveButton().click();
+    await twitch.click();
+    await expect.poll(() => embeds.length).toBe(2);
+    const twitchUrl = new URL(embeds[1].url());
+    expect(twitchUrl.origin).toBe('https://player.twitch.tv');
+    expect(twitchUrl.searchParams.get('parent')).toBe(new URL(page.url()).hostname);
+
+    await liveButton().click();
+    await youtube.click();
+    await expect.poll(() => embeds.length).toBe(3);
+    expect(embeds[2].url()).toBe(embeds[0].url());
+    expect(await embeds[2].headerValue('referer')).toBe(expectedReferrer);
+
+    await pip.close();
+    await expect(liveButton()).toHaveAttribute('data-pip-open', 'false');
+    await expect(liveButton()).toHaveAttribute('data-live', 'true');
+    await expect(page).toHaveURL(/\/docs\/$/);
+
+    await liveButton().click();
+    const reopened = context.waitForEvent('page');
+    await youtube.click();
+    const nextPip = await reopened;
+    await expect.poll(() => embeds.length).toBe(4);
+    expect(await embeds[3].headerValue('referer')).toBe(expectedReferrer);
+    await nextPip.close();
+    await expect(liveButton()).toHaveAttribute('data-pip-open', 'false');
+  });
+}