diff --git a/src/Logto.AspNetCore.Authentication/LogtoOptions.cs b/src/Logto.AspNetCore.Authentication/LogtoOptions.cs
index 079b770..42df1a3 100644
--- a/src/Logto.AspNetCore.Authentication/LogtoOptions.cs
+++ b/src/Logto.AspNetCore.Authentication/LogtoOptions.cs
@@ -63,6 +63,10 @@ public class LogtoOptions
   /// set this value to `true` since they are not included in the ID token.
   /// </summary>
   public bool GetClaimsFromUserInfoEndpoint { get; set; } = false;
+  /// <summary>
+  /// The domain to associate the cookie with. Allows multiple applications to share the cookie such as on sub-domains. 
+  /// </summary>
+  public string? CookieDomain { get; set; } = null;
 }
 
 /// <summary>
@@ -78,4 +82,5 @@ public static class PromptMode
   /// The user will be prompted for sign-in again anyway. Note there will be no refresh token returned in this case.
   /// </summary>
   public const string Login = "login";
+
 }
diff --git a/src/Logto.AspNetCore.Authentication/extensions/AuthenticationBuilderExtensions.cs b/src/Logto.AspNetCore.Authentication/extensions/AuthenticationBuilderExtensions.cs
index cc3f76e..46b2086 100644
--- a/src/Logto.AspNetCore.Authentication/extensions/AuthenticationBuilderExtensions.cs
+++ b/src/Logto.AspNetCore.Authentication/extensions/AuthenticationBuilderExtensions.cs
@@ -73,6 +73,7 @@ private static void ConfigureCookieOptions(string authenticationScheme, CookieAu
   {
     options.Cookie.Name = $"Logto.Cookie.{logtoOptions.AppId}";
     options.SlidingExpiration = true;
+    options.Cookie.Domain = logtoOptions.CookieDomain;
     options.Events = new CookieAuthenticationEvents
     {
       OnValidatePrincipal = context => new LogtoCookieContextManager(authenticationScheme, context).Handle()