diff --git a/x-pack/plugins/stack_alerts/public/alert_types/es_query/expression/es_query_expression.tsx b/x-pack/plugins/stack_alerts/public/alert_types/es_query/expression/es_query_expression.tsx
index 10b774648d735a..afb45f90c6e52f 100644
--- a/x-pack/plugins/stack_alerts/public/alert_types/es_query/expression/es_query_expression.tsx
+++ b/x-pack/plugins/stack_alerts/public/alert_types/es_query/expression/es_query_expression.tsx
@@ -83,6 +83,7 @@ export const EsQueryExpression = ({
     thresholdComparator: thresholdComparator ?? DEFAULT_VALUES.THRESHOLD_COMPARATOR,
     size: size ?? DEFAULT_VALUES.SIZE,
     esQuery: esQuery ?? DEFAULT_VALUES.QUERY,
+    searchType: 'esQuery',
   });
 
   const setParam = useCallback(
diff --git a/x-pack/plugins/stack_alerts/server/alert_types/es_query/alert_type_params.ts b/x-pack/plugins/stack_alerts/server/alert_types/es_query/alert_type_params.ts
index 74bbad6f81fcc6..d3be171a38dea8 100644
--- a/x-pack/plugins/stack_alerts/server/alert_types/es_query/alert_type_params.ts
+++ b/x-pack/plugins/stack_alerts/server/alert_types/es_query/alert_type_params.ts
@@ -34,30 +34,30 @@ const EsQueryAlertParamsSchemaProperties = {
   timeWindowUnit: schema.string({ validate: validateTimeWindowUnits }),
   threshold: schema.arrayOf(schema.number(), { minSize: 1, maxSize: 2 }),
   thresholdComparator: getComparatorSchemaType(validateComparator),
-  searchType: schema.maybe(schema.literal('searchSource')),
+  searchType: schema.oneOf([schema.literal('searchSource'), schema.literal('esQuery')]),
   // searchSource alert param only
   searchConfiguration: schema.conditional(
     schema.siblingRef('searchType'),
-    schema.never(),
-    schema.never(),
-    schema.object({}, { unknowns: 'allow' })
+    schema.literal('searchSource'),
+    schema.object({}, { unknowns: 'allow' }),
+    schema.never()
   ),
   // esQuery alert params only
   esQuery: schema.conditional(
     schema.siblingRef('searchType'),
-    schema.never(),
+    schema.literal('esQuery'),
     schema.string({ minLength: 1 }),
     schema.never()
   ),
   index: schema.conditional(
     schema.siblingRef('searchType'),
-    schema.never(),
+    schema.literal('esQuery'),
     schema.arrayOf(schema.string({ minLength: 1 }), { minSize: 1 }),
     schema.never()
   ),
   timeField: schema.conditional(
     schema.siblingRef('searchType'),
-    schema.never(),
+    schema.literal('esQuery'),
     schema.string({ minLength: 1 }),
     schema.never()
   ),