diff --git a/x-pack/plugins/index_lifecycle_management/public/application/store/selectors/policies.js b/x-pack/plugins/index_lifecycle_management/public/application/store/selectors/policies.js
index 32c6d93383c22..f0a8e4d81ebe3 100644
--- a/x-pack/plugins/index_lifecycle_management/public/application/store/selectors/policies.js
+++ b/x-pack/plugins/index_lifecycle_management/public/application/store/selectors/policies.js
@@ -193,8 +193,15 @@ const phaseFromES = (phase, phaseName, defaultEmptyPolicy) => {
     }
 
     if (actions.set_priority) {
-      policy[PHASE_INDEX_PRIORITY] = actions.set_priority.priority;
+      const { priority } = actions.set_priority;
+
+      if (priority) {
+        policy[PHASE_INDEX_PRIORITY] = priority;
+      } else {
+        policy[PHASE_INDEX_PRIORITY] = '';
+      }
     }
+
     if (actions.wait_for_snapshot) {
       policy[PHASE_WAIT_FOR_SNAPSHOT_POLICY] = actions.wait_for_snapshot.policy;
     }
@@ -311,6 +318,10 @@ export const phaseToES = (phase, originalEsPhase) => {
     esPhase.actions.set_priority = {
       priority: phase[PHASE_INDEX_PRIORITY],
     };
+  } else if (phase[PHASE_INDEX_PRIORITY] === '') {
+    esPhase.actions.set_priority = {
+      priority: null,
+    };
   }
 
   if (phase[PHASE_WAIT_FOR_SNAPSHOT_POLICY]) {
diff --git a/x-pack/plugins/index_lifecycle_management/server/routes/api/policies/register_create_route.ts b/x-pack/plugins/index_lifecycle_management/server/routes/api/policies/register_create_route.ts
index 7bf3f96e2b2ef..a35255b3f65ad 100644
--- a/x-pack/plugins/index_lifecycle_management/server/routes/api/policies/register_create_route.ts
+++ b/x-pack/plugins/index_lifecycle_management/server/routes/api/policies/register_create_route.ts
@@ -30,7 +30,7 @@ const minAgeSchema = schema.maybe(schema.string());
 
 const setPrioritySchema = schema.maybe(
   schema.object({
-    priority: schema.number(),
+    priority: schema.nullable(schema.number()),
   })
 );