diff --git a/types/chrome/index.d.ts b/types/chrome/index.d.ts
index de869d11ae..1644be7c66 100644
--- a/types/chrome/index.d.ts
+++ b/types/chrome/index.d.ts
@@ -4153,6 +4153,34 @@ declare namespace chrome.input.ime {
     export var onReset: InputResetEvent;
 }
 
+////////////////////
+// LoginState
+////////////////////
+/**
+ * Use the chrome.loginState API to read and monitor the login state.
+ * Permissions: "loginState"
+ * @since Chrome 78.
+ * Important: This API works only on Chrome OS.
+ */
+declare namespace chrome.loginState {
+    export interface SessionStateChangedEvent extends chrome.events.Event<(sessionState: SessionState) => void> { }
+
+    /** Possible profile types. */
+    export type ProfileType = 'SIGNIN_PROFILE'|'USER_PROFILE';
+
+    /** Possible session states. */
+    export type SessionState = 'UNKNOWN'|'IN_OOBE_SCREEN'|'IN_LOGIN_SCREEN'|'IN_SESSION'|'IN_LOCK_SCREEN';
+
+    /** Gets the type of the profile the extension is in. */
+    export function getProfileType(callback: (profileType: ProfileType) => void): void;
+
+    /** Gets the current session state. */
+    export function getSessionState(callback: (sessionState: SessionState) => void): void;
+
+    /** Dispatched when the session state changes. sessionState is the new session state.*/
+    export const onSessionStateChanged: SessionStateChangedEvent;
+}
+
 ////////////////////
 // Management
 ////////////////////