diff --git a/x-pack/plugins/ml/server/routes/schemas/anomaly_detectors_schema.ts b/x-pack/plugins/ml/server/routes/schemas/anomaly_detectors_schema.ts
index 6002bb218c41b..22c3d94dfb29e 100644
--- a/x-pack/plugins/ml/server/routes/schemas/anomaly_detectors_schema.ts
+++ b/x-pack/plugins/ml/server/routes/schemas/anomaly_detectors_schema.ts
@@ -35,10 +35,13 @@ const customUrlSchema = {
   time_range: schema.maybe(schema.any()),
 };
 
-const customSettingsSchema = schema.object({
-  created_by: schema.maybe(schema.string()),
-  custom_urls: schema.maybe(schema.arrayOf(schema.maybe(schema.object({ ...customUrlSchema })))),
-});
+const customSettingsSchema = schema.object(
+  {
+    created_by: schema.maybe(schema.string()),
+    custom_urls: schema.maybe(schema.arrayOf(schema.maybe(schema.object({ ...customUrlSchema })))),
+  },
+  { unknowns: 'allow' } // Create / Update job API allows other fields to be added to custom_settings.
+);
 
 export const anomalyDetectionUpdateJobSchema = {
   description: schema.maybe(schema.string()),