diff --git a/litellm/proxy/auth/master_key_policy.py b/litellm/proxy/auth/master_key_policy.py
index 318b722b0ff..eeb7d3ee72a 100644
--- a/litellm/proxy/auth/master_key_policy.py
+++ b/litellm/proxy/auth/master_key_policy.py
@@ -3,13 +3,20 @@ from typing import Final
 INSECURE_MASTER_KEYS: Final = frozenset({"sk-1234"})
 
 
-def insecure_master_key_warning(master_key: str | None) -> str | None:
-    if master_key not in INSECURE_MASTER_KEYS:
-        return None
-    return (
-        "LITELLM_MASTER_KEY is set to the example key 'sk-1234' from the docs. "
-        "Anyone who has read the docs can administer this gateway, and publicly reachable "
-        "gateways using this key have been compromised. Set a strong random master key "
-        "(e.g. `python -c \"import secrets; print('sk-' + secrets.token_urlsafe(32))\"`). "
-        "A future release will refuse to start with this key."
-    )
+def insecure_master_key_warning(master_key: str | None, alternative_auth_enabled: bool) -> str | None:
+    if master_key in INSECURE_MASTER_KEYS:
+        return (
+            "LITELLM_MASTER_KEY is set to the example key 'sk-1234' from the docs. "
+            "Anyone who has read the docs can administer this gateway, and publicly reachable "
+            "gateways using this key have been compromised. Set a strong random master key "
+            "(e.g. `python -c \"import secrets; print('sk-' + secrets.token_urlsafe(32))\"`). "
+            "A future release will refuse to start with this key."
+        )
+    if (master_key is None or master_key == "") and not alternative_auth_enabled:
+        return (
+            "No master key is set (LITELLM_MASTER_KEY or general_settings.master_key). "
+            "Every request to this proxy is accepted without authentication, including "
+            'admin routes. Set a strong random master key (e.g. `python -c "import secrets; '
+            "print('sk-' + secrets.token_urlsafe(32))\"`) before exposing it to a network."
+        )
+    return None
diff --git a/litellm/proxy/proxy_server.py b/litellm/proxy/proxy_server.py
index 5aa75e360f2..805c61d4697 100644
--- a/litellm/proxy/proxy_server.py
+++ b/litellm/proxy/proxy_server.py
@@ -1160,7 +1160,12 @@ async def proxy_startup_event(app: FastAPI) -> AsyncGenerator[None, None]:
             if isinstance(worker_config, dict):
                 await initialize(**worker_config)
 
-    _insecure_master_key_warning: Final = insecure_master_key_warning(master_key)
+    _alternative_auth_enabled: Final = any(
+        general_settings.get(k, False) for k in ("enable_jwt_auth", "enable_oauth2_auth", "enable_oauth2_proxy_auth")
+    )
+    _insecure_master_key_warning: Final = insecure_master_key_warning(
+        master_key, alternative_auth_enabled=_alternative_auth_enabled
+    )
     if _insecure_master_key_warning is not None:
         verbose_proxy_logger.warning(_insecure_master_key_warning)
 
diff --git a/tests/test_litellm/proxy/auth/test_master_key_policy.py b/tests/test_litellm/proxy/auth/test_master_key_policy.py
index 6c949fc3783..6b118994cba 100644
--- a/tests/test_litellm/proxy/auth/test_master_key_policy.py
+++ b/tests/test_litellm/proxy/auth/test_master_key_policy.py
@@ -3,22 +3,36 @@ from litellm.proxy.auth.master_key_policy import insecure_master_key_warning
 
 
 def test_insecure_master_key_warning_returned_for_example_key():
-    warning = insecure_master_key_warning("sk-1234")
+    warning = insecure_master_key_warning("sk-1234", alternative_auth_enabled=False)
 
     assert warning is not None
     assert "sk-1234" in warning
 
 
+def test_insecure_master_key_warning_for_missing_key():
+    warning = insecure_master_key_warning(None, alternative_auth_enabled=False)
+
+    assert warning is not None
+    assert "No master key" in warning
+
+
+def test_insecure_master_key_warning_for_empty_key():
+    warning = insecure_master_key_warning("", alternative_auth_enabled=False)
+
+    assert warning is not None
+    assert "No master key" in warning
+
+
+def test_insecure_master_key_warning_none_for_missing_key_with_alt_auth():
+    assert insecure_master_key_warning(None, alternative_auth_enabled=True) is None
+
+
 def test_insecure_master_key_warning_none_for_strong_key():
-    assert insecure_master_key_warning("sk-strong-random-key") is None
-
-
-def test_insecure_master_key_warning_none_for_none():
-    assert insecure_master_key_warning(None) is None
+    assert insecure_master_key_warning("sk-strong-random-key", alternative_auth_enabled=False) is None
 
 
 def test_insecure_master_key_warning_survives_redaction():
-    warning = insecure_master_key_warning("sk-1234")
+    warning = insecure_master_key_warning("sk-1234", alternative_auth_enabled=False)
 
     assert warning is not None
     assert "secrets.token_urlsafe" in redact_string(warning)
diff --git a/tests/test_litellm/proxy/proxy_server/test_lifecycle.py b/tests/test_litellm/proxy/proxy_server/test_lifecycle.py
index 775e9443653..d472e3935de 100644
--- a/tests/test_litellm/proxy/proxy_server/test_lifecycle.py
+++ b/tests/test_litellm/proxy/proxy_server/test_lifecycle.py
@@ -1090,3 +1090,20 @@ async def test_proxy_startup_event_warns_but_does_not_raise_for_docs_example_mas
         pass
 
     assert "sk-1234" in caplog.text, "startup should log the insecure master key warning"
+
+
+@pytest.mark.asyncio
+async def test_proxy_startup_event_warns_but_does_not_raise_for_missing_master_key(monkeypatch, caplog):
+    monkeypatch.delenv("LITELLM_MASTER_KEY", raising=False)
+
+    try:
+        with caplog.at_level(logging.WARNING, logger="LiteLLM Proxy"):
+            async with proxy_startup_event(app=None):
+                pass
+    except ValueError as e:
+        if "master key" in str(e).lower():
+            pytest.fail("proxy_startup_event refused to boot without a master key")
+    except Exception:
+        pass
+
+    assert "No master key" in caplog.text, "startup should log the missing master key warning"