diff --git a/.changeset/nostalgic-tireless-kestrel.md b/.changeset/nostalgic-tireless-kestrel.md
new file mode 100644
index 00000000..e7bd4fb9
--- /dev/null
+++ b/.changeset/nostalgic-tireless-kestrel.md
@@ -0,0 +1,5 @@
+---
+"stagehand": patch
+---
+
+Add LLM customization support (eg. api_base)
diff --git a/stagehand/config.py b/stagehand/config.py
index a577230d..8805e40b 100644
--- a/stagehand/config.py
+++ b/stagehand/config.py
@@ -20,6 +20,7 @@ class StagehandConfig(BaseModel):
         browserbase_session_id (Optional[str]): Session ID for resuming Browserbase sessions.
         model_name (Optional[str]): Name of the model to use.
         model_api_key (Optional[str]): Model API key.
+        model_client_options (Optional[dict[str, Any]]): Options for the model client.
         logger (Optional[Callable[[Any], None]]): Custom logging function.
         verbose (Optional[int]): Verbosity level for logs (1=minimal, 2=medium, 3=detailed).
         use_rich_logging (bool): Whether to use Rich for colorized logging.
@@ -50,6 +51,11 @@ class StagehandConfig(BaseModel):
     model_api_key: Optional[str] = Field(
         None, alias="modelApiKey", description="Model API key"
     )
+    model_client_options: Optional[dict[str, Any]] = Field(
+        None,
+        alias="modelClientOptions",
+        description="Configuration options for the language model client (i.e. api_base)",
+    )
     verbose: Optional[int] = Field(
         1,
         description="Verbosity level for logs: 0=minimal (ERROR), 1=medium (INFO), 2=detailed (DEBUG)",
diff --git a/stagehand/llm/client.py b/stagehand/llm/client.py
index ac0ead4a..e9fbefe5 100644
--- a/stagehand/llm/client.py
+++ b/stagehand/llm/client.py
@@ -54,7 +54,7 @@ def __init__(
                 setattr(litellm, key, value)
                 self.logger.debug(f"Set global litellm.{key}", category="llm")
             # Handle common aliases or expected config names if necessary
-            elif key == "api_base":  # Example: map api_base if needed
+            elif key == "api_base" or key == "baseURL":
                 litellm.api_base = value
                 self.logger.debug(
                     f"Set global litellm.api_base to {value}", category="llm"
diff --git a/stagehand/main.py b/stagehand/main.py
index 4a201adb..03d6d45f 100644
--- a/stagehand/main.py
+++ b/stagehand/main.py
@@ -161,7 +161,11 @@ def __init__(
 
         # Handle non-config parameters
         self.api_url = self.config.api_url
+
+        # Handle model-related settings
+        self.model_client_options = self.config.model_client_options or {}
         self.model_api_key = self.config.model_api_key or os.getenv("MODEL_API_KEY")
+
         self.model_name = self.config.model_name
 
         # Extract frequently used values from config for convenience
@@ -181,11 +185,11 @@ def __init__(
         self.local_browser_launch_options = (
             self.config.local_browser_launch_options or {}
         )
-
-        # Handle model-related settings
-        self.model_client_options = {}
-        if self.model_api_key and "apiKey" not in self.model_client_options:
+        if self.model_api_key:
             self.model_client_options["apiKey"] = self.model_api_key
+        else:
+            if "apiKey" in self.model_client_options:
+                self.model_api_key = self.model_client_options["apiKey"]
 
         # Handle browserbase session create params
         self.browserbase_session_create_params = make_serializable(
diff --git a/tests/unit/llm/test_llm_integration.py b/tests/unit/llm/test_llm_integration.py
index a01e7a73..00d09c40 100644
--- a/tests/unit/llm/test_llm_integration.py
+++ b/tests/unit/llm/test_llm_integration.py
@@ -40,6 +40,7 @@ def test_llm_client_with_custom_options(self):
             api_key="test-key",
             default_model="gpt-4o-mini",
             stagehand_logger=StagehandLogger(),
+            api_base="https://test-api-base.com",
         )
         
         assert client.default_model == "gpt-4o-mini"
diff --git a/tests/unit/test_client_initialization.py b/tests/unit/test_client_initialization.py
index 237ada9b..afec5c6b 100644
--- a/tests/unit/test_client_initialization.py
+++ b/tests/unit/test_client_initialization.py
@@ -228,3 +228,32 @@ async def mock_create_session():
         # Call _create_session and expect error
         with pytest.raises(RuntimeError, match="Invalid response format"):
             await client._create_session()
+
+    @mock.patch.dict(os.environ, {"MODEL_API_KEY": "test-model-api-key"}, clear=True)
+    def test_init_with_model_api_key_in_env(self):
+        config = StagehandConfig(env="LOCAL")
+        client = Stagehand(config=config)
+        assert client.model_api_key == "test-model-api-key"
+
+    def test_init_with_custom_llm(self):
+        config = StagehandConfig(
+            env="LOCAL",
+            model_client_options={"apiKey": "custom-llm-key", "baseURL": "https://custom-llm.com"}
+        )
+        client = Stagehand(config=config)
+        assert client.model_api_key == "custom-llm-key"
+        assert client.model_client_options["apiKey"] == "custom-llm-key"
+        assert client.model_client_options["baseURL"] == "https://custom-llm.com"
+
+    def test_init_with_custom_llm_override(self):
+        config = StagehandConfig(
+            env="LOCAL",
+            model_client_options={"apiKey": "custom-llm-key", "baseURL": "https://custom-llm.com"}
+        )
+        client = Stagehand(
+            config=config,
+            model_client_options={"apiKey": "override-llm-key", "baseURL": "https://override-llm.com"}
+        )
+        assert client.model_api_key == "override-llm-key"
+        assert client.model_client_options["apiKey"] == "override-llm-key"
+        assert client.model_client_options["baseURL"] == "https://override-llm.com"
\ No newline at end of file