diff --git a/portkey_ai/__init__.py b/portkey_ai/__init__.py
index 10479a8b..52fd9344 100644
--- a/portkey_ai/__init__.py
+++ b/portkey_ai/__init__.py
@@ -164,6 +164,13 @@
     PORTKEY_PROXY_ENV,
     PORTKEY_GATEWAY_URL,
 )
+from portkey_ai.utils.json_utils import (
+    PortkeyJSONEncoder,
+    enable_notgiven_serialization,
+    disable_notgiven_serialization,
+)
+    
+enable_notgiven_serialization()
 
 api_key = os.environ.get(PORTKEY_API_KEY_ENV)
 base_url = os.environ.get(PORTKEY_PROXY_ENV, PORTKEY_BASE_URL)
@@ -175,6 +182,9 @@
     "LLMOptions",
     "Modes",
     "PortkeyResponse",
+    "PortkeyJSONEncoder",
+    "enable_notgiven_serialization",
+    "disable_notgiven_serialization",
     "ModesLiteral",
     "ProviderTypes",
     "ProviderTypesLiteral",
diff --git a/portkey_ai/utils/json_utils.py b/portkey_ai/utils/json_utils.py
index 6b016caf..a302dcbc 100644
--- a/portkey_ai/utils/json_utils.py
+++ b/portkey_ai/utils/json_utils.py
@@ -1,33 +1,64 @@
 import json
+from portkey_ai._vendor.openai._utils import is_given
 
 
-def serialize_kwargs(**kwargs):
-    # Function to check if a value is serializable
-    def is_serializable(value):
-        try:
-            json.dumps(value)
-            return True
-        except (TypeError, ValueError):
-            return False
+_BASE_JSON_DEFAULT = json.JSONEncoder.default
+_patched_notgiven_serialization = False
+
+
+class PortkeyJSONEncoder(json.JSONEncoder):
+    """JSON encoder that treats OpenAI/Portkey "not provided" markers as null."""
+
+    def default(self, obj):  # type: ignore[override]
+        # If this is one of OpenAI's internal "not provided" / omit markers,
+        # encode it as None (null in JSON) instead of raising TypeError.
+        if not is_given(obj):
+            return None
+        return super().default(obj)
+
+
+def enable_notgiven_serialization() -> None:
+    """Globally encode NotGiven / Omit markers as null in json.dumps."""
+    global _patched_notgiven_serialization
+    if _patched_notgiven_serialization:
+        return
+
+    def patched_default(self, obj):  # type: ignore[override]
+        if not is_given(obj):
+            return None
+        return _BASE_JSON_DEFAULT(self, obj)
 
-    # Filter out non-serializable items
-    serializable_kwargs = {k: v for k, v in kwargs.items() if is_serializable(v)}
+    json.JSONEncoder.default = patched_default
+    _patched_notgiven_serialization = True
 
-    # Convert to string representation
-    return json.dumps(serializable_kwargs)
+
+def disable_notgiven_serialization() -> None:
+    """Restore the original json.JSONEncoder.default implementation."""
+    global _patched_notgiven_serialization
+    if not _patched_notgiven_serialization:
+        return
+
+    json.JSONEncoder.default = _BASE_JSON_DEFAULT
+    _patched_notgiven_serialization = False
+
+
+def _is_serializable(value) -> bool:
+    try:
+        json.dumps(value, cls=PortkeyJSONEncoder)
+    except (TypeError, ValueError):
+        return False
+    return True
+
+
+def serialize_kwargs(**kwargs):
+    return json.dumps(
+        {k: v for k, v in kwargs.items() if _is_serializable(v)},
+        cls=PortkeyJSONEncoder,
+    )
 
 
 def serialize_args(*args):
-    # Function to check if a value is serializable
-    def is_serializable(value):
-        try:
-            json.dumps(value)
-            return True
-        except (TypeError, ValueError):
-            return False
-
-    # Filter out non-serializable items
-    serializable_args = [arg for arg in args if is_serializable(arg)]
-
-    # Convert to string representation
-    return json.dumps(serializable_args)
+    return json.dumps(
+        [arg for arg in args if _is_serializable(arg)],
+        cls=PortkeyJSONEncoder,
+    )