diff --git a/litellm/types/proxy/management_endpoints/key_requests.py b/litellm/types/proxy/management_endpoints/key_requests.py
index baa02b68d98..58b5951dd3b 100644
--- a/litellm/types/proxy/management_endpoints/key_requests.py
+++ b/litellm/types/proxy/management_endpoints/key_requests.py
@@ -54,6 +54,16 @@ class LiteLLMKeyType(str, enum.Enum):
     DEFAULT = "default"  # Uses default allowed routes
 
 
+def _is_mapping(value: object) -> TypeIs[Mapping[object, object]]:  # guard-ok: raw before-validator payload
+    return isinstance(value, Mapping)
+
+
+def _reject_expires(values: object) -> object:
+    if _is_mapping(values) and "expires" in values:
+        raise ValueError('expires is not supported on key requests. Set duration instead, e.g. "3600s" or "30d"')
+    return values
+
+
 class GenerateKeyRequest(KeyRequestBase):
     soft_budget: float | None = None
     send_invite_email: bool | None = None
@@ -69,6 +79,11 @@ class GenerateKeyRequest(KeyRequestBase):
     organization_id: str | None = None
     project_id: str | None = None
 
+    @model_validator(mode="before")
+    @classmethod
+    def reject_expires(cls, values: object) -> object:
+        return _reject_expires(values)
+
     @field_validator("team_id", "organization_id", "project_id", mode="before")
     @classmethod
     def treat_cleared_id_as_unset(cls, v: object) -> object:
@@ -77,10 +92,6 @@ class GenerateKeyRequest(KeyRequestBase):
         return v
 
 
-def _is_mapping(value: object) -> TypeIs[Mapping[object, object]]:  # guard-ok: raw before-validator payload
-    return isinstance(value, Mapping)
-
-
 class UpdateKeyRequest(KeyRequestBase):
     # Note: the defaults of all Params here MUST BE NONE
     # else they will get overwritten
@@ -99,6 +110,11 @@ class UpdateKeyRequest(KeyRequestBase):
         description="Omit to retain the project, or send null to detach. Assigning a different project is not supported.",
     )
 
+    @model_validator(mode="before")
+    @classmethod
+    def reject_expires(cls, values: object) -> object:
+        return _reject_expires(values)
+
     @model_validator(mode="before")
     @classmethod
     def drop_blank_team_id(cls, values: object) -> object:
diff --git a/tests/unit/proxy/management_endpoints/test_key_management_endpoints.py b/tests/unit/proxy/management_endpoints/test_key_management_endpoints.py
index d6ee9b1d29e..28118cd96c1 100644
--- a/tests/unit/proxy/management_endpoints/test_key_management_endpoints.py
+++ b/tests/unit/proxy/management_endpoints/test_key_management_endpoints.py
@@ -15,7 +15,7 @@ from fastapi.testclient import TestClient
 from unittest.mock import AsyncMock, MagicMock, patch
 
 from fastapi import HTTPException
-from pydantic import JsonValue
+from pydantic import JsonValue, ValidationError
 
 import inspect
 
@@ -108,6 +108,28 @@ from litellm.types.proxy.management_endpoints.key_management_endpoints import (
 client = TestClient(app)
 
 
+def test_key_request_models_reject_expires() -> None:
+    for request_model, request_values in (
+        (GenerateKeyRequest, {"expires": "2026-01-01T00:00:00Z"}),
+        (UpdateKeyRequest, {"key": "sk-x", "expires": "2026-01-01T00:00:00Z"}),
+        (RegenerateKeyRequest, {"expires": "2026-01-01T00:00:00Z"}),
+        (GenerateKeyRequest, {"expires": None}),
+    ):
+        with pytest.raises(ValidationError) as exc_info:
+            request_model.model_validate(request_values)
+        assert "duration" in str(exc_info.value)
+
+
+def test_generate_key_response_preserves_expires() -> None:
+    expires: Final = datetime(2026, 1, 1, tzinfo=timezone.utc)
+
+    assert GenerateKeyResponse(key="sk-x", expires=expires).expires == expires
+
+
+def test_generate_key_request_accepts_duration_without_expires() -> None:
+    assert GenerateKeyRequest.model_validate({"duration": "1h"}).duration == "1h"
+
+
 @pytest.mark.asyncio
 async def test_list_keys():
     mock_prisma_client = AsyncMock()
@@ -23305,5 +23327,3 @@ def test_key_info_database_not_connected_sanitized_500(
     finally:
         proxy_server.app.dependency_overrides.pop(user_api_key_auth, None)
 
-
-