diff --git a/.changeset/bright-mangos-grow.md b/.changeset/bright-mangos-grow.md
new file mode 100644
index 0000000000..cc646fe669
--- /dev/null
+++ b/.changeset/bright-mangos-grow.md
@@ -0,0 +1,8 @@
+---
+'@clerk/backend': minor
+---
+
+Update Session resource with new properties to align with OpenAPI spec
+- `lastActiveOrganizationId`
+- `latestActivity`
+- `actor`
diff --git a/packages/backend/src/api/resources/JSON.ts b/packages/backend/src/api/resources/JSON.ts
index 0c5c544ba6..852c454614 100644
--- a/packages/backend/src/api/resources/JSON.ts
+++ b/packages/backend/src/api/resources/JSON.ts
@@ -229,13 +229,25 @@ export interface RedirectUrlJSON extends ClerkResourceJSON {
   updated_at: number;
 }
 
+export interface SessionActivityJSON extends ClerkResourceJSON {
+  id: string;
+  device_type?: string;
+  is_mobile: boolean;
+  browser_name?: string;
+  browser_version?: string;
+  ip_address?: string;
+  city?: string;
+  country?: string;
+}
+
 export interface SessionJSON extends ClerkResourceJSON {
   object: typeof ObjectType.Session;
   client_id: string;
   user_id: string;
   status: string;
   last_active_organization_id?: string;
-  actor?: Record<string, unknown>;
+  actor: Record<string, unknown> | null;
+  latest_activity?: SessionActivityJSON;
   last_active_at: number;
   expire_at: number;
   abandon_at: number;
diff --git a/packages/backend/src/api/resources/Session.ts b/packages/backend/src/api/resources/Session.ts
index cd0e3ea982..9ba0f0b469 100644
--- a/packages/backend/src/api/resources/Session.ts
+++ b/packages/backend/src/api/resources/Session.ts
@@ -1,4 +1,30 @@
-import type { SessionJSON } from './JSON';
+import type { SessionActivityJSON, SessionJSON } from './JSON';
+
+export class SessionActivity {
+  constructor(
+    readonly id: string,
+    readonly isMobile: boolean,
+    readonly ipAddress?: string,
+    readonly city?: string,
+    readonly country?: string,
+    readonly browserVersion?: string,
+    readonly browserName?: string,
+    readonly deviceType?: string,
+  ) {}
+
+  static fromJSON(data: SessionActivityJSON): SessionActivity {
+    return new SessionActivity(
+      data.id,
+      data.is_mobile,
+      data.ip_address,
+      data.city,
+      data.country,
+      data.browser_version,
+      data.browser_name,
+      data.device_type,
+    );
+  }
+}
 
 export class Session {
   constructor(
@@ -11,6 +37,9 @@ export class Session {
     readonly abandonAt: number,
     readonly createdAt: number,
     readonly updatedAt: number,
+    readonly lastActiveOrganizationId?: string,
+    readonly latestActivity?: SessionActivity,
+    readonly actor: Record<string, unknown> | null = null,
   ) {}
 
   static fromJSON(data: SessionJSON): Session {
@@ -24,6 +53,9 @@ export class Session {
       data.abandon_at,
       data.created_at,
       data.updated_at,
+      data.last_active_organization_id,
+      data.latest_activity && SessionActivity.fromJSON(data.latest_activity),
+      data.actor,
     );
   }
 }