diff --git a/autogen/agentchat/groupchat.py b/autogen/agentchat/groupchat.py
index f6e5d30264b..3e01139a1cb 100644
--- a/autogen/agentchat/groupchat.py
+++ b/autogen/agentchat/groupchat.py
@@ -1160,7 +1160,7 @@ async def a_run_chat(
     def resume(
         self,
         messages: Union[List[Dict], str],
-        remove_termination_string: str = None,
+        remove_termination_string: Union[str, Callable[[str], str]] = None,
         silent: Optional[bool] = False,
     ) -> Tuple[ConversableAgent, Dict]:
         """Resumes a group chat using the previous messages as a starting point. Requires the agents, group chat, and group chat manager to be established
@@ -1168,7 +1168,9 @@ def resume(
 
         Args:
             - messages Union[List[Dict], str]: The content of the previous chat's messages, either as a Json string or a list of message dictionaries.
-            - remove_termination_string str: Remove the provided string from the last message to prevent immediate termination
+            - remove_termination_string (str or function): Remove the termination string from the last message to prevent immediate termination
+                If a string is provided, this string will be removed from last message.
+                If a function is provided, the last message will be passed to this function.
             - silent (bool or None): (Experimental) whether to print the messages for this conversation. Default is False.
 
         Returns:
@@ -1263,7 +1265,7 @@ def resume(
     async def a_resume(
         self,
         messages: Union[List[Dict], str],
-        remove_termination_string: str = None,
+        remove_termination_string: Union[str, Callable[[str], str]],
         silent: Optional[bool] = False,
     ) -> Tuple[ConversableAgent, Dict]:
         """Resumes a group chat using the previous messages as a starting point, asynchronously. Requires the agents, group chat, and group chat manager to be established
@@ -1271,7 +1273,9 @@ async def a_resume(
 
         Args:
             - messages Union[List[Dict], str]: The content of the previous chat's messages, either as a Json string or a list of message dictionaries.
-            - remove_termination_string str: Remove the provided string from the last message to prevent immediate termination
+            - remove_termination_string (str or function): Remove the termination string from the last message to prevent immediate termination
+                If a string is provided, this string will be removed from last message.
+                If a function is provided, the last message will be passed to this function, and the function returns the string after processing.
             - silent (bool or None): (Experimental) whether to print the messages for this conversation. Default is False.
 
         Returns:
@@ -1390,11 +1394,15 @@ def _valid_resume_messages(self, messages: List[Dict]):
                 ):
                     raise Exception(f"Agent name in message doesn't exist as agent in group chat: {message['name']}")
 
-    def _process_resume_termination(self, remove_termination_string: str, messages: List[Dict]):
+    def _process_resume_termination(
+        self, remove_termination_string: Union[str, Callable[[str], str]], messages: List[Dict]
+    ):
         """Removes termination string, if required, and checks if termination may occur.
 
         args:
-            remove_termination_string (str): termination string to remove from the last message
+            remove_termination_string (str or function): Remove the termination string from the last message to prevent immediate termination
+                If a string is provided, this string will be removed from last message.
+                If a function is provided, the last message will be passed to this function, and the function returns the string after processing.
 
         returns:
             None
@@ -1403,9 +1411,17 @@ def _process_resume_termination(self, remove_termination_string: str, messages:
         last_message = messages[-1]
 
         # Replace any given termination string in the last message
-        if remove_termination_string:
-            if messages[-1].get("content") and remove_termination_string in messages[-1]["content"]:
-                messages[-1]["content"] = messages[-1]["content"].replace(remove_termination_string, "")
+        if isinstance(remove_termination_string, str):
+
+            def _remove_termination_string(content: str) -> str:
+                return content.replace(remove_termination_string, "")
+
+        else:
+            _remove_termination_string = remove_termination_string
+
+        if _remove_termination_string:
+            if messages[-1].get("content"):
+                messages[-1]["content"] = _remove_termination_string(messages[-1]["content"])
 
         # Check if the last message meets termination (if it has one)
         if self._is_termination_msg:
diff --git a/test/agentchat/test_groupchat.py b/test/agentchat/test_groupchat.py
index 933b4ce7df2..20a83685178 100755
--- a/test/agentchat/test_groupchat.py
+++ b/test/agentchat/test_groupchat.py
@@ -1916,6 +1916,51 @@ def test_manager_resume_functions():
     # TERMINATE should be removed
     assert messages[-1]["content"] == final_msg.replace("TERMINATE", "")
 
+    # Tests termination message replacement with function
+    def termination_func(x: str) -> str:
+        if "APPROVED" in x:
+            x = x.replace("APPROVED", "")
+        else:
+            x = x.replace("TERMINATE", "")
+        return x
+
+    final_msg1 = "Product_Manager has created 3 new product ideas. APPROVED"
+    messages1 = [
+        {
+            "content": "You are an expert at finding the next speaker.",
+            "role": "system",
+        },
+        {
+            "content": final_msg1,
+            "name": "Coder",
+            "role": "assistant",
+        },
+    ]
+
+    manager._process_resume_termination(remove_termination_string=termination_func, messages=messages1)
+
+    # APPROVED should be removed
+    assert messages1[-1]["content"] == final_msg1.replace("APPROVED", "")
+
+    final_msg2 = "Idea has been approved. TERMINATE"
+    messages2 = [
+        {
+            "content": "You are an expert at finding the next speaker.",
+            "role": "system",
+        },
+        {
+            "content": final_msg2,
+            "name": "Coder",
+            "role": "assistant",
+        },
+    ]
+
+    manager._process_resume_termination(remove_termination_string=termination_func, messages=messages2)
+
+    # TERMINATE should be removed, "approved" should still be present as the termination_func only replaces upper-cased "APPROVED".
+    assert messages2[-1]["content"] == final_msg2.replace("TERMINATE", "")
+    assert "approved" in messages2[-1]["content"]
+
     # Check if the termination string doesn't exist there's no replacing of content
     final_msg = (
         "Let's get this meeting started. First the Product_Manager will create 3 new product ideas. TERMINATE this."
@@ -2027,7 +2072,7 @@ def test_manager_resume_messages():
     # test_clear_agents_history()
     # test_custom_speaker_selection_overrides_transition_graph()
     # test_role_for_select_speaker_messages()
-    test_select_speaker_message_and_prompt_templates()
+    # test_select_speaker_message_and_prompt_templates()
     # test_speaker_selection_agent_name_match()
     # test_role_for_reflection_summary()
     # test_speaker_selection_auto_process_result()
@@ -2036,7 +2081,7 @@ def test_manager_resume_messages():
     # test_select_speaker_auto_messages()
     # test_manager_messages_to_string()
     # test_manager_messages_from_string()
-    # test_manager_resume_functions()
+    test_manager_resume_functions()
     # test_manager_resume_returns()
     # test_manager_resume_messages()
     pass