diff --git a/litellm/llms/custom_httpx/http_handler.py b/litellm/llms/custom_httpx/http_handler.py
index e1f0fc9e7d3..e2413469264 100644
--- a/litellm/llms/custom_httpx/http_handler.py
+++ b/litellm/llms/custom_httpx/http_handler.py
@@ -163,6 +163,17 @@ def _default_cached_client_timeout() -> httpx.Timeout:
     return httpx.Timeout(timeout=configured, connect=HTTP_HANDLER_CONNECT_TIMEOUT_SECONDS)
 
 
+def _resolve_effective_timeout(timeout: float | httpx.Timeout | None) -> float | httpx.Timeout:
+    """Resolve the timeout actually in effect for a request.
+
+    `None` means "use the client default", which `create_client` maps to
+    `_DEFAULT_TIMEOUT`. An explicit `timeout=None` handed to httpx bypasses the
+    client default entirely (no timeouts are enforced), so `None` must be
+    resolved before building a request or rendering a Timeout error message.
+    """
+    return timeout if timeout is not None else _DEFAULT_TIMEOUT
+
+
 _CLIENT_REFCOUNT_WHEN_HANDLER_IS_SOLE_REFERRER: Final = 2
 
 
@@ -687,7 +698,7 @@ class AsyncHTTPHandler:
         start_time: Final = time.time()
         try:
             if timeout is None:
-                timeout = self.timeout
+                timeout = _resolve_effective_timeout(self.timeout)
 
             # Prepare data/content parameters to prevent httpx DeprecationWarning (memory leak fix)
             request_data, request_content = _prepare_request_data_and_content(data, content)
@@ -754,7 +765,7 @@ class AsyncHTTPHandler:
     ):
         try:
             if timeout is None:
-                timeout = self.timeout
+                timeout = _resolve_effective_timeout(self.timeout)
 
             # Prepare data/content parameters to prevent httpx DeprecationWarning (memory leak fix)
             request_data, request_content = _prepare_request_data_and_content(data, content)
@@ -818,7 +829,7 @@ class AsyncHTTPHandler:
     ):
         try:
             if timeout is None:
-                timeout = self.timeout
+                timeout = _resolve_effective_timeout(self.timeout)
 
             # Prepare data/content parameters to prevent httpx DeprecationWarning (memory leak fix)
             request_data, request_content = _prepare_request_data_and_content(data, content)
@@ -882,7 +893,7 @@ class AsyncHTTPHandler:
     ):
         try:
             if timeout is None:
-                timeout = self.timeout
+                timeout = _resolve_effective_timeout(self.timeout)
 
             # Prepare data/content parameters to prevent httpx DeprecationWarning (memory leak fix)
             request_data, request_content = _prepare_request_data_and_content(data, content)
@@ -1366,7 +1377,7 @@ class HTTPHandler:
             return response
         except httpx.TimeoutException:
             raise litellm.Timeout(
-                message=f"Connection timed out after {timeout} seconds.",
+                message=f"Connection timed out after {_resolve_effective_timeout(timeout)} seconds.",
                 model="default-model-name",
                 llm_provider="litellm-httpx-handler",
             )
@@ -1416,7 +1427,7 @@ class HTTPHandler:
             return response
         except httpx.TimeoutException:
             raise litellm.Timeout(
-                message=f"Connection timed out after {timeout} seconds.",
+                message=f"Connection timed out after {_resolve_effective_timeout(timeout)} seconds.",
                 model="default-model-name",
                 llm_provider="litellm-httpx-handler",
             )
@@ -1465,7 +1476,7 @@ class HTTPHandler:
             return response
         except httpx.TimeoutException:
             raise litellm.Timeout(
-                message=f"Connection timed out after {timeout} seconds.",
+                message=f"Connection timed out after {_resolve_effective_timeout(timeout)} seconds.",
                 model="default-model-name",
                 llm_provider="litellm-httpx-handler",
             )
@@ -1515,7 +1526,7 @@ class HTTPHandler:
             return response
         except httpx.TimeoutException:
             raise litellm.Timeout(
-                message=f"Connection timed out after {timeout} seconds.",
+                message=f"Connection timed out after {_resolve_effective_timeout(timeout)} seconds.",
                 model="default-model-name",
                 llm_provider="litellm-httpx-handler",
             )
diff --git a/tests/test_litellm/llms/custom_httpx/test_http_handler.py b/tests/test_litellm/llms/custom_httpx/test_http_handler.py
index 9e64bfafa54..3aa65a94ded 100644
--- a/tests/test_litellm/llms/custom_httpx/test_http_handler.py
+++ b/tests/test_litellm/llms/custom_httpx/test_http_handler.py
@@ -14,6 +14,7 @@ import pytest
 from aiohttp import ClientSession, TCPConnector
 
 import litellm
+from litellm.constants import COMPLETION_HTTP_FALLBACK_SECONDS, HTTP_HANDLER_CONNECT_TIMEOUT_SECONDS
 from litellm.llms.custom_httpx.aiohttp_transport import LiteLLMAiohttpTransport
 from litellm.llms.custom_httpx.http_handler import (
     _CLIENT_REFCOUNT_WHEN_HANDLER_IS_SOLE_REFERRER,
@@ -1547,3 +1548,66 @@ def test_sync_force_ipv4_https_proxy_mount_uses_handler_ca_bundle(
         handler.close()
 
     assert response.text == "ok-tls"
+class _TimeoutRecordingAsyncClient(httpx.AsyncClient):
+    async def send(self, request, **kwargs):
+        self.sent_timeout_extensions = request.extensions.get("timeout")
+        raise httpx.ConnectTimeout("connect timed out", request=request)
+
+
+class _RecordingSyncClient(httpx.Client):
+    def send(self, request, **kwargs):
+        raise httpx.ReadTimeout("read timed out", request=request)
+
+
+@pytest.mark.asyncio
+async def test_async_post_without_timeout_enforces_default_and_reports_it():
+    """
+    A handler built without a timeout used to pass timeout=None straight to
+    httpx, which bypasses the client default entirely (no timeouts enforced)
+    and produced "Connection timed out after None seconds." on failure.
+    """
+    handler = AsyncHTTPHandler()
+    assert handler.timeout is None
+    client = _TimeoutRecordingAsyncClient()
+    handler.client = client
+
+    with pytest.raises(litellm.Timeout) as exc_info:
+        await handler.post("https://example.test/v1/chat", json={"ping": True})
+
+    assert client.sent_timeout_extensions["connect"] == HTTP_HANDLER_CONNECT_TIMEOUT_SECONDS
+    assert client.sent_timeout_extensions["read"] == COMPLETION_HTTP_FALLBACK_SECONDS
+    assert "None seconds" not in str(exc_info.value)
+    assert f"{COMPLETION_HTTP_FALLBACK_SECONDS}" in str(exc_info.value)
+
+
+@pytest.mark.asyncio
+async def test_async_post_explicit_timeout_is_enforced_and_reported():
+    handler = AsyncHTTPHandler()
+    handler.client = _TimeoutRecordingAsyncClient()
+
+    with pytest.raises(litellm.Timeout) as exc_info:
+        await handler.post("https://example.test/v1/chat", json={"ping": True}, timeout=3.5)
+
+    assert "None seconds" not in str(exc_info.value)
+    assert "3.5" in str(exc_info.value)
+
+
+def test_sync_post_timeout_message_reports_client_default_when_timeout_unset():
+    handler = HTTPHandler()
+    handler.client = _RecordingSyncClient()
+
+    with pytest.raises(litellm.Timeout) as exc_info:
+        handler.post("https://example.test/v1/chat", json={"ping": True})
+
+    assert "None seconds" not in str(exc_info.value)
+    assert f"{COMPLETION_HTTP_FALLBACK_SECONDS}" in str(exc_info.value)
+
+
+def test_sync_post_timeout_message_reports_explicit_timeout():
+    handler = HTTPHandler()
+    handler.client = _RecordingSyncClient()
+
+    with pytest.raises(litellm.Timeout) as exc_info:
+        handler.post("https://example.test/v1/chat", json={"ping": True}, timeout=3.5)
+
+    assert "3.5 seconds" in str(exc_info.value)