diff --git a/docs/my-website/docs/proxy/config_settings.md b/docs/my-website/docs/proxy/config_settings.md
index 23c0b1498f..bfaa2776fa 100644
--- a/docs/my-website/docs/proxy/config_settings.md
+++ b/docs/my-website/docs/proxy/config_settings.md
@@ -199,6 +199,7 @@ router_settings:
 | use_chat_completions_url_for_anthropic_messages | boolean | If true, routes OpenAI `/v1/messages` requests through chat/completions instead of the Responses API. Can also be set via env var `LITELLM_USE_CHAT_COMPLETIONS_URL_FOR_ANTHROPIC_MESSAGES=true`. |
 | disable_hf_tokenizer_download | boolean | If true, it defaults to using the openai tokenizer for all models (including huggingface models). |
 | enable_json_schema_validation | boolean | If true, enables json schema validation for all requests. |
+| enable_key_alias_format_validation | boolean | If true, validates `key_alias` format on `/key/generate` and `/key/update`. Must be 2-255 chars, start/end with alphanumeric, only allow `a-zA-Z0-9_-/.@`. Default `false`. |
 | disable_copilot_system_to_assistant | boolean | **DEPRECATED** - GitHub Copilot API supports system prompts. |
 
 ### general_settings - Reference
diff --git a/litellm/__init__.py b/litellm/__init__.py
index d75f47567a..4fc71e1270 100644
--- a/litellm/__init__.py
+++ b/litellm/__init__.py
@@ -305,6 +305,9 @@ return_response_headers: bool = (
     False  # get response headers from LLM Api providers - example x-remaining-requests,
 )
 enable_json_schema_validation: bool = False
+enable_key_alias_format_validation: bool = (
+    False  # opt-in validation of key_alias format on /key/generate and /key/update
+)
 ####################
 logging: bool = True
 enable_loadbalancing_on_batch_endpoints: Optional[bool] = None
diff --git a/litellm/proxy/management_endpoints/key_management_endpoints.py b/litellm/proxy/management_endpoints/key_management_endpoints.py
index 072d4181c6..3b54a79a73 100644
--- a/litellm/proxy/management_endpoints/key_management_endpoints.py
+++ b/litellm/proxy/management_endpoints/key_management_endpoints.py
@@ -5041,12 +5041,18 @@ def _validate_key_alias_format(key_alias: Optional[str]) -> None:
     """
     Validate the format of the key_alias.
 
-    Rules:
+    Gated behind ``litellm.enable_key_alias_format_validation`` (default **False**).
+    When disabled, no validation is performed so existing workflows are not broken.
+
+    Rules (when enabled):
     - None is OK (no alias).
     - Otherwise must be 2–255 chars
     - start/end with alphanumeric
-    - only allow a-zA-Z0-9_-/.
+    - only allow a-zA-Z0-9_-/.@
     """
+    if not litellm.enable_key_alias_format_validation:
+        return
+
     if key_alias is None:
         return
 
diff --git a/tests/test_litellm/proxy/management_endpoints/test_key_management_endpoints.py b/tests/test_litellm/proxy/management_endpoints/test_key_management_endpoints.py
index 2533f0d66d..6195f34f28 100644
--- a/tests/test_litellm/proxy/management_endpoints/test_key_management_endpoints.py
+++ b/tests/test_litellm/proxy/management_endpoints/test_key_management_endpoints.py
@@ -2,6 +2,7 @@ import json
 import os
 import sys
 
+import litellm
 import pytest
 import yaml
 from fastapi.testclient import TestClient
@@ -6672,8 +6673,26 @@ async def test_key_aliases_admin_sees_all():
 
 
 class TestValidateKeyAliasFormat:
+    @pytest.fixture(autouse=True)
+    def reset_key_alias_flag(self):
+        litellm.enable_key_alias_format_validation = False
+        yield
+        litellm.enable_key_alias_format_validation = False
+
+    def test_validation_skipped_when_flag_disabled(self):
+        """When enable_key_alias_format_validation is False (default), no validation occurs."""
+        from litellm.proxy.management_endpoints.key_management_endpoints import _validate_key_alias_format
+
+        # Even invalid aliases should pass silently when the flag is off
+        _validate_key_alias_format(None)
+        _validate_key_alias_format("")
+        _validate_key_alias_format("!invalid!")
+        _validate_key_alias_format("a" * 256)
+
     def test_validate_key_alias_format_valid(self):
         from litellm.proxy.management_endpoints.key_management_endpoints import _validate_key_alias_format
+
+        litellm.enable_key_alias_format_validation = True
         # Valid cases
         _validate_key_alias_format(None)  # OK
         _validate_key_alias_format("valid-alias")
@@ -6688,7 +6707,8 @@ class TestValidateKeyAliasFormat:
     def test_validate_key_alias_format_invalid(self):
         from litellm.proxy.management_endpoints.key_management_endpoints import _validate_key_alias_format
         from litellm.proxy._types import ProxyException
-        
+
+        litellm.enable_key_alias_format_validation = True
         invalid_aliases = [
             "",               # empty
             " ",              # whitespace
@@ -6701,7 +6721,7 @@ class TestValidateKeyAliasFormat:
             "  leading",
             "trailing  ",
         ]
-        
+
         for alias in invalid_aliases:
             with pytest.raises(ProxyException) as exc:
                 _validate_key_alias_format(alias)