diff --git a/x-pack/platform/plugins/shared/security/server/session_management/session_index.test.ts b/x-pack/platform/plugins/shared/security/server/session_management/session_index.test.ts
index d0fb5a5d70f5e..f454cd553c14c 100644
--- a/x-pack/platform/plugins/shared/security/server/session_management/session_index.test.ts
+++ b/x-pack/platform/plugins/shared/security/server/session_management/session_index.test.ts
@@ -66,7 +66,7 @@ describe('Session index', () => {
         name: indexTemplateName,
       });
       expect(mockElasticsearchClient.indices.exists).toHaveBeenCalledWith({
-        index: getSessionIndexSettings({ indexName, aliasName }).index,
+        index: aliasName,
       });
     }
 
@@ -96,7 +96,7 @@ describe('Session index', () => {
 
       expect(mockElasticsearchClient.indices.deleteTemplate).not.toHaveBeenCalled();
       expect(mockElasticsearchClient.indices.putIndexTemplate).not.toHaveBeenCalled();
-      expect(mockElasticsearchClient.indices.putAlias).toHaveBeenCalledTimes(1);
+      expect(mockElasticsearchClient.indices.putAlias).not.toHaveBeenCalled();
       expect(mockElasticsearchClient.indices.create).not.toHaveBeenCalled();
     });
 
@@ -116,7 +116,7 @@ describe('Session index', () => {
 
       expect(mockElasticsearchClient.indices.deleteTemplate).not.toHaveBeenCalled();
       expect(mockElasticsearchClient.indices.deleteIndexTemplate).not.toHaveBeenCalled();
-      expect(mockElasticsearchClient.indices.putAlias).not.toHaveBeenCalled();
+      expect(mockElasticsearchClient.indices.putAlias).toHaveBeenCalledTimes(1);
       expect(mockElasticsearchClient.indices.getMapping).not.toHaveBeenCalled();
       expect(mockElasticsearchClient.indices.putMapping).not.toHaveBeenCalled();
       expect(mockElasticsearchClient.indices.create).toHaveBeenCalledWith(
@@ -140,7 +140,7 @@ describe('Session index', () => {
 
       expect(mockElasticsearchClient.indices.deleteTemplate).not.toHaveBeenCalled();
       expect(mockElasticsearchClient.indices.deleteIndexTemplate).not.toHaveBeenCalled();
-      expect(mockElasticsearchClient.indices.putAlias).not.toHaveBeenCalled();
+      expect(mockElasticsearchClient.indices.putAlias).toHaveBeenCalledTimes(1);
       expect(mockElasticsearchClient.indices.getMapping).not.toHaveBeenCalled();
       expect(mockElasticsearchClient.indices.putMapping).not.toHaveBeenCalled();
       expect(mockElasticsearchClient.indices.create).toHaveBeenCalledWith(
@@ -162,7 +162,7 @@ describe('Session index', () => {
       expect(mockElasticsearchClient.indices.create).toHaveBeenCalledWith(
         getSessionIndexSettings({ indexName, aliasName })
       );
-      expect(mockElasticsearchClient.indices.putAlias).not.toHaveBeenCalled();
+      expect(mockElasticsearchClient.indices.putAlias).toHaveBeenCalledTimes(1);
     });
 
     it('deletes legacy & modern index templates if needed and creates index if it does not exist', async () => {
@@ -182,7 +182,7 @@ describe('Session index', () => {
       expect(mockElasticsearchClient.indices.create).toHaveBeenCalledWith(
         getSessionIndexSettings({ indexName, aliasName })
       );
-      expect(mockElasticsearchClient.indices.putAlias).not.toHaveBeenCalled();
+      expect(mockElasticsearchClient.indices.putAlias).toHaveBeenCalledTimes(1);
     });
 
     it('deletes modern index template if needed and creates index if it does not exist', async () => {
@@ -197,7 +197,7 @@ describe('Session index', () => {
       expect(mockElasticsearchClient.indices.deleteIndexTemplate).toHaveBeenCalledWith({
         name: indexTemplateName,
       });
-      expect(mockElasticsearchClient.indices.putAlias).not.toHaveBeenCalled();
+      expect(mockElasticsearchClient.indices.putAlias).toHaveBeenCalledTimes(1);
       expect(mockElasticsearchClient.indices.create).toHaveBeenCalledWith(
         getSessionIndexSettings({ indexName, aliasName })
       );
@@ -216,11 +216,7 @@ describe('Session index', () => {
       expect(mockElasticsearchClient.indices.deleteIndexTemplate).not.toHaveBeenCalled();
       expect(mockElasticsearchClient.indices.create).not.toHaveBeenCalled();
 
-      expect(mockElasticsearchClient.indices.putAlias).toHaveBeenCalledTimes(1);
-      expect(mockElasticsearchClient.indices.putAlias).toHaveBeenCalledWith({
-        index: indexName,
-        name: aliasName,
-      });
+      expect(mockElasticsearchClient.indices.putAlias).not.toHaveBeenCalled();
     });
 
     it('updates mappings for existing index without version in the meta', async () => {
@@ -241,16 +237,13 @@ describe('Session index', () => {
       expect(mockElasticsearchClient.indices.deleteIndexTemplate).not.toHaveBeenCalled();
       expect(mockElasticsearchClient.indices.create).not.toHaveBeenCalled();
 
-      expect(mockElasticsearchClient.indices.putAlias).toHaveBeenCalledTimes(1);
-      expect(mockElasticsearchClient.indices.putAlias).toHaveBeenCalledWith({
-        index: indexName,
-        name: aliasName,
-      });
+      expect(mockElasticsearchClient.indices.putAlias).not.toHaveBeenCalled();
+
       expect(mockElasticsearchClient.indices.getMapping).toHaveBeenCalledTimes(1);
-      expect(mockElasticsearchClient.indices.getMapping).toHaveBeenCalledWith({ index: indexName });
+      expect(mockElasticsearchClient.indices.getMapping).toHaveBeenCalledWith({ index: aliasName });
       expect(mockElasticsearchClient.indices.putMapping).toHaveBeenCalledTimes(1);
       expect(mockElasticsearchClient.indices.putMapping).toHaveBeenCalledWith({
-        index: indexName,
+        index: aliasName,
         ...getSessionIndexSettings({ indexName, aliasName }).mappings,
       });
     });
@@ -273,16 +266,13 @@ describe('Session index', () => {
       expect(mockElasticsearchClient.indices.deleteIndexTemplate).not.toHaveBeenCalled();
       expect(mockElasticsearchClient.indices.create).not.toHaveBeenCalled();
 
-      expect(mockElasticsearchClient.indices.putAlias).toHaveBeenCalledTimes(1);
-      expect(mockElasticsearchClient.indices.putAlias).toHaveBeenCalledWith({
-        index: indexName,
-        name: aliasName,
-      });
+      expect(mockElasticsearchClient.indices.putAlias).not.toHaveBeenCalled();
+
       expect(mockElasticsearchClient.indices.getMapping).toHaveBeenCalledTimes(1);
-      expect(mockElasticsearchClient.indices.getMapping).toHaveBeenCalledWith({ index: indexName });
+      expect(mockElasticsearchClient.indices.getMapping).toHaveBeenCalledWith({ index: aliasName });
       expect(mockElasticsearchClient.indices.putMapping).toHaveBeenCalledTimes(1);
       expect(mockElasticsearchClient.indices.putMapping).toHaveBeenCalledWith({
-        index: indexName,
+        index: aliasName,
         ...getSessionIndexSettings({ indexName, aliasName }).mappings,
       });
     });
@@ -305,13 +295,10 @@ describe('Session index', () => {
       expect(mockElasticsearchClient.indices.deleteIndexTemplate).not.toHaveBeenCalled();
       expect(mockElasticsearchClient.indices.create).not.toHaveBeenCalled();
 
-      expect(mockElasticsearchClient.indices.putAlias).toHaveBeenCalledTimes(1);
-      expect(mockElasticsearchClient.indices.putAlias).toHaveBeenCalledWith({
-        index: indexName,
-        name: aliasName,
-      });
+      expect(mockElasticsearchClient.indices.putAlias).not.toHaveBeenCalled();
+
       expect(mockElasticsearchClient.indices.getMapping).toHaveBeenCalledTimes(1);
-      expect(mockElasticsearchClient.indices.getMapping).toHaveBeenCalledWith({ index: indexName });
+      expect(mockElasticsearchClient.indices.getMapping).toHaveBeenCalledWith({ index: aliasName });
       expect(mockElasticsearchClient.indices.putMapping).not.toHaveBeenCalled();
     });
 
@@ -325,7 +312,7 @@ describe('Session index', () => {
       assertExistenceChecksPerformed();
       expect(mockElasticsearchClient.indices.deleteTemplate).not.toHaveBeenCalled();
       expect(mockElasticsearchClient.indices.deleteIndexTemplate).not.toHaveBeenCalled();
-      expect(mockElasticsearchClient.indices.putAlias).not.toHaveBeenCalled();
+      expect(mockElasticsearchClient.indices.putAlias).toHaveBeenCalledTimes(1);
       expect(mockElasticsearchClient.indices.getMapping).not.toHaveBeenCalled();
       expect(mockElasticsearchClient.indices.putMapping).not.toHaveBeenCalled();
       expect(mockElasticsearchClient.indices.create).toHaveBeenCalledWith(
@@ -462,7 +449,7 @@ describe('Session index', () => {
 
       expect(mockElasticsearchClient.indices.exists).toHaveBeenCalledTimes(1);
       expect(mockElasticsearchClient.indices.create).toHaveBeenCalledTimes(1);
-      expect(mockElasticsearchClient.indices.putAlias).not.toHaveBeenCalled();
+      expect(mockElasticsearchClient.indices.putAlias).toHaveBeenCalledTimes(1);
       expect(mockElasticsearchClient.search).toHaveBeenCalledTimes(1);
       expect(mockElasticsearchClient.bulk).toHaveBeenCalledTimes(1);
       expect(mockElasticsearchClient.closePointInTime).toHaveBeenCalledTimes(1); // since we attempted to delete sessions, we still refresh the index
@@ -1445,7 +1432,7 @@ describe('Session index', () => {
 
       expect(mockElasticsearchClient.indices.exists).toHaveBeenCalledTimes(1);
       expect(mockElasticsearchClient.indices.create).toHaveBeenCalledTimes(1);
-      expect(mockElasticsearchClient.indices.putAlias).not.toHaveBeenCalled();
+      expect(mockElasticsearchClient.indices.putAlias).toHaveBeenCalledTimes(1);
 
       expect(mockElasticsearchClient.create).toHaveBeenCalledTimes(2);
       expect(mockElasticsearchClient.create).toHaveBeenNthCalledWith(
diff --git a/x-pack/platform/plugins/shared/security/server/session_management/session_index.ts b/x-pack/platform/plugins/shared/security/server/session_management/session_index.ts
index 1dc4ecc1ec4a9..c266d76c03677 100644
--- a/x-pack/platform/plugins/shared/security/server/session_management/session_index.ts
+++ b/x-pack/platform/plugins/shared/security/server/session_management/session_index.ts
@@ -633,7 +633,7 @@ export class SessionIndex {
     let indexExists = false;
     try {
       indexExists = await this.options.elasticsearchClient.indices.exists({
-        index: this.indexName,
+        index: this.aliasName,
       });
     } catch (err) {
       this.options.logger.error(`Failed to check if session index exists: ${err.message}`);
@@ -662,6 +662,20 @@ export class SessionIndex {
         }
       }
 
+      // Prior to https://github.com/elastic/kibana/pull/134900, sessions would be written directly against the session index.
+      // Now, we write sessions against a new session index alias. This call ensures that the alias exists, and is attached to the index.
+      // This operation is safe to repeat, even if the alias already exists. This seems safer than retrieving the index details, and inspecting
+      // it to see if the alias already exists.
+      try {
+        await this.options.elasticsearchClient.indices.putAlias({
+          index: this.indexName,
+          name: this.aliasName,
+        });
+      } catch (err) {
+        this.options.logger.error(`Failed to attach alias to session index: ${err.message}`);
+        throw err;
+      }
+
       return;
     }
 
@@ -669,26 +683,11 @@ export class SessionIndex {
       'Session index already exists. Attaching alias to the index and ensuring up-to-date mappings...'
     );
 
-    // Prior to https://github.com/elastic/kibana/pull/134900, sessions would be written directly against the session index.
-    // Now, we write sessions against a new session index alias. This call ensures that the alias exists, and is attached to the index.
-    // This operation is safe to repeat, even if the alias already exists. This seems safer than retrieving the index details, and inspecting
-    // it to see if the alias already exists.
-    try {
-      await this.options.elasticsearchClient.indices.putAlias({
-        index: this.indexName,
-        name: this.aliasName,
-      });
-    } catch (err) {
-      this.options.logger.error(`Failed to attach alias to session index: ${err.message}`);
-      throw err;
-    }
-
     let indexMappingsVersion: string | undefined;
     try {
       const indexMappings = await this.options.elasticsearchClient.indices.getMapping({
-        index: this.indexName,
+        index: this.aliasName,
       });
-
       indexMappingsVersion =
         indexMappings[this.indexName]?.mappings?._meta?.[
           SESSION_INDEX_MAPPINGS_VERSION_META_FIELD_NAME
@@ -706,7 +705,7 @@ export class SessionIndex {
       );
       try {
         await this.options.elasticsearchClient.indices.putMapping({
-          index: this.indexName,
+          index: this.aliasName,
           ...sessionIndexSettings.mappings,
         });
         this.options.logger.debug('Successfully updated session index mappings.');