diff --git a/packages/jupyter-ai/jupyter_ai/config_manager.py b/packages/jupyter-ai/jupyter_ai/config_manager.py
index 71ca3f185..7b309faae 100644
--- a/packages/jupyter-ai/jupyter_ai/config_manager.py
+++ b/packages/jupyter-ai/jupyter_ai/config_manager.py
@@ -442,10 +442,10 @@ def em_provider_params(self):
     @property
     def completions_lm_provider_params(self):
         return self._provider_params(
-            "completions_model_provider_id", self._lm_providers
+            "completions_model_provider_id", self._lm_providers, completions=True
         )
 
-    def _provider_params(self, key, listing):
+    def _provider_params(self, key, listing, completions: bool = False):
         # read config
         config = self._read_config()
 
@@ -457,7 +457,10 @@ def _provider_params(self, key, listing):
         model_id = model_uid.split(":", 1)[1]
 
         # get config fields (e.g. base API URL, etc.)
-        fields = config.fields.get(model_uid, {})
+        if completions:
+            fields = config.completions_fields.get(model_uid, {})
+        else:
+            fields = config.fields.get(model_uid, {})
 
         # get authn fields
         _, Provider = get_em_provider(model_uid, listing)
diff --git a/packages/jupyter-ai/jupyter_ai/tests/test_config_manager.py b/packages/jupyter-ai/jupyter_ai/tests/test_config_manager.py
index 168c675f7..4a739f6e5 100644
--- a/packages/jupyter-ai/jupyter_ai/tests/test_config_manager.py
+++ b/packages/jupyter-ai/jupyter_ai/tests/test_config_manager.py
@@ -194,20 +194,35 @@ def configure_to_openai(cm: ConfigManager):
     return LM_GID, EM_GID, LM_LID, EM_LID, API_PARAMS
 
 
-def configure_with_fields(cm: ConfigManager):
+def configure_with_fields(cm: ConfigManager, completions: bool = False):
     """
-    Configures the ConfigManager with fields and API keys.
+    Default behavior: Configures the ConfigManager with fields and API keys.
     Returns the expected result of `cm.lm_provider_params`.
+
+    If `completions` is set to `True`, this configures the ConfigManager with
+    completion model fields, and returns the expected result of
+    `cm.completions_lm_provider_params`.
     """
-    req = UpdateConfigRequest(
-        model_provider_id="openai-chat:gpt-4o",
-        api_keys={"OPENAI_API_KEY": "foobar"},
-        fields={
-            "openai-chat:gpt-4o": {
-                "openai_api_base": "https://example.com",
-            }
-        },
-    )
+    if completions:
+        req = UpdateConfigRequest(
+            completions_model_provider_id="openai-chat:gpt-4o",
+            api_keys={"OPENAI_API_KEY": "foobar"},
+            completions_fields={
+                "openai-chat:gpt-4o": {
+                    "openai_api_base": "https://example.com",
+                }
+            },
+        )
+    else:
+        req = UpdateConfigRequest(
+            model_provider_id="openai-chat:gpt-4o",
+            api_keys={"OPENAI_API_KEY": "foobar"},
+            fields={
+                "openai-chat:gpt-4o": {
+                    "openai_api_base": "https://example.com",
+                }
+            },
+        )
     cm.update_config(req)
     return {
         "model_id": "gpt-4o",
@@ -445,7 +460,7 @@ def test_handle_bad_provider_ids(cm_with_bad_provider_ids):
     assert config_desc.embeddings_provider_id is None
 
 
-def test_config_manager_returns_fields(cm):
+def test_returns_chat_model_fields(cm):
     """
     Asserts that `ConfigManager.lm_provider_params` returns model fields set by
     the user.
@@ -454,6 +469,11 @@ def test_config_manager_returns_fields(cm):
     assert cm.lm_provider_params == expected_model_args
 
 
+def test_returns_completion_model_fields(cm):
+    expected_model_args = configure_with_fields(cm, completions=True)
+    assert cm.completions_lm_provider_params == expected_model_args
+
+
 def test_config_manager_does_not_write_to_defaults(
     config_file_with_model_fields, schema_path
 ):