diff --git a/.changelog/4954.fixed b/.changelog/4954.fixed
new file mode 100644
index 0000000000..724f7e96d5
--- /dev/null
+++ b/.changelog/4954.fixed
@@ -0,0 +1 @@
+`opentelemetry-instrumentation-openai-v2`: fix `server.address` on openai 3.x
diff --git a/instrumentation-genai/opentelemetry-instrumentation-openai-v2/src/opentelemetry/instrumentation/openai_v2/utils.py b/instrumentation-genai/opentelemetry-instrumentation-openai-v2/src/opentelemetry/instrumentation/openai_v2/utils.py
index 0bbaf39ccc..7ca43d0649 100644
--- a/instrumentation-genai/opentelemetry-instrumentation-openai-v2/src/opentelemetry/instrumentation/openai_v2/utils.py
+++ b/instrumentation-genai/opentelemetry-instrumentation-openai-v2/src/opentelemetry/instrumentation/openai_v2/utils.py
@@ -9,7 +9,6 @@
 from urllib.parse import urlparse
 
 import openai
-from httpx import URL
 from openai import NotGiven
 
 from opentelemetry._logs import LogRecord
@@ -91,13 +90,14 @@ def get_server_address_and_port(
     base_url = getattr(base_client, "base_url", None)
     if not base_url:
         return None, None
-    address = None
-    port = None
-    if isinstance(base_url, URL):
-        address = base_url.host
-        port = base_url.port
-    elif isinstance(base_url, str):
-        url = urlparse(base_url)
+
+    # Read the URL structurally rather than by type. openai 3.x builds on httpx2, so base_url is an
+    # httpx2.URL rather than an httpx.URL, and an isinstance check against either one silently stops
+    # matching when the SDK changes its HTTP client.
+    address = getattr(base_url, "host", None)
+    port = getattr(base_url, "port", None)
+    if address is None:
+        url = urlparse(str(base_url))
         address = url.hostname
         port = url.port
 
diff --git a/instrumentation-genai/opentelemetry-instrumentation-openai-v2/tests/test_server_address.py b/instrumentation-genai/opentelemetry-instrumentation-openai-v2/tests/test_server_address.py
new file mode 100644
index 0000000000..7b1a9c9902
--- /dev/null
+++ b/instrumentation-genai/opentelemetry-instrumentation-openai-v2/tests/test_server_address.py
@@ -0,0 +1,96 @@
+# Copyright The OpenTelemetry Authors
+# SPDX-License-Identifier: Apache-2.0
+
+"""Tests for endpoint extraction in `get_server_address_and_port`.
+
+The extraction must not depend on which HTTP client library the OpenAI SDK happens to use internally.
+openai 3.x builds on httpx2, so `client._client.base_url` is an `httpx2.URL`; an isinstance check against
+`httpx.URL` silently stops matching and `server.address` disappears from every span.
+"""
+
+import subprocess
+import sys
+import textwrap
+from importlib.metadata import version
+
+import pytest
+
+from opentelemetry.instrumentation.openai_v2.utils import (
+    get_server_address_and_port,
+)
+
+
+class _Client:
+    """Stands in for the resource object the instrumentation receives (e.g. `client.chat.completions`),
+    whose `_client` is the SDK client holding `base_url`."""
+
+    def __init__(self, base_url):
+        self._client = type("Inner", (), {"base_url": base_url})()
+
+
+def test_httpx_url():
+    httpx = pytest.importorskip("httpx")
+    address, port = get_server_address_and_port(_Client(httpx.URL("http://localhost:8080/v1")))
+    assert address == "localhost"
+    assert port == 8080
+
+
+def test_httpx2_url():
+    httpx2 = pytest.importorskip("httpx2")
+    address, port = get_server_address_and_port(_Client(httpx2.URL("http://localhost:8080/v1")))
+    assert address == "localhost"
+    assert port == 8080
+
+
+def test_string_base_url():
+    address, port = get_server_address_and_port(_Client("http://localhost:8080/v1"))
+    assert address == "localhost"
+    assert port == 8080
+
+
+def test_default_https_port_is_omitted():
+    address, port = get_server_address_and_port(_Client("https://api.openai.com:443/v1"))
+    assert address == "api.openai.com"
+    assert port is None
+
+
+def test_missing_base_url():
+    assert get_server_address_and_port(_Client(None)) == (None, None)
+    assert get_server_address_and_port(object()) == (None, None)
+
+
+def test_importable_without_httpx():
+    """The module must import when httpx is not installed.
+
+    This package declares no dependency on httpx, and openai 3.x depends on httpx2 instead, so httpx can
+    legitimately be absent. A module-scope `from httpx import URL` then makes the instrumentation
+    unimportable rather than merely degraded.
+
+    Skipped on openai 2.x, which imports httpx itself, so the situation cannot arise there.
+    """
+    if int(version("openai").split(".")[0]) < 3:
+        pytest.skip("openai 2.x depends on httpx itself, so httpx is never absent")
+    script = textwrap.dedent(
+        """
+        import sys
+
+        class Blocker:
+            def find_spec(self, name, path=None, target=None):
+                if name == "httpx" or name.startswith("httpx."):
+                    raise ModuleNotFoundError("No module named 'httpx'")
+                return None
+
+        sys.meta_path.insert(0, Blocker())
+        for module in [m for m in sys.modules if m == "httpx" or m.startswith("httpx.")]:
+            del sys.modules[module]
+
+        from opentelemetry.instrumentation.openai_v2 import OpenAIInstrumentor  # noqa: F401
+        """
+    )
+    result = subprocess.run(
+        [sys.executable, "-c", script],
+        capture_output=True,
+        text=True,
+        check=False,
+    )
+    assert result.returncode == 0, result.stderr