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 a3aef8679817d..23b6b5298752d 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
@@ -192,7 +192,9 @@ const phaseFromES = (phase, phaseName, defaultEmptyPolicy) => {
     }
 
     if (actions.set_priority) {
-      policy[PHASE_INDEX_PRIORITY] = actions.set_priority.priority;
+      const { priority } = actions.set_priority;
+
+      policy[PHASE_INDEX_PRIORITY] = priority ?? '';
     }
   }
   return policy;
@@ -307,6 +309,10 @@ 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,
+    };
   }
   return esPhase;
 };
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 aac92f3e41a2d..c7ef1acff2fc0 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()),
   })
 );