diff --git a/Base/usr/share/man/man8/usermod.md b/Base/usr/share/man/man8/usermod.md
index 97108d680d..e522150db7 100644
--- a/Base/usr/share/man/man8/usermod.md
+++ b/Base/usr/share/man/man8/usermod.md
@@ -5,7 +5,7 @@ usermod - modify a user account
 ## Synopsis
 
 ```sh
-$ usermod [--uid uid] [--gid group] [--lock] [--unlock] [--home new-home] [--move] [--shell path-to-shell] [--gecos general-info] <username>
+$ usermod [--uid uid] [--gid group] [--groups groups] [--lock] [--unlock] [--home new-home] [--move] [--shell path-to-shell] [--gecos general-info] <username>
 ```
 
 ## Description
@@ -19,6 +19,7 @@ This program must be run as root.
 * `--version`: Print version
 * `-u uid`, `--uid uid`: The new numerical value of the user's ID
 * `-g group`, `--gid group`: The group name or number of the user's new initial login group
+* `-G groups`, `--groups groups`: Set the user's supplementary groups. Groups are specified with a comma-separated list. Group names or numbers may be used
 * `-L`, `--lock`: Lock password
 * `-U`, `--unlock`: Unlock password
 * `-d new-home`, `--home new-home`: The user's new login directory
diff --git a/Userland/Utilities/usermod.cpp b/Userland/Utilities/usermod.cpp
index a2b6413c39..0d79cb0f84 100644
--- a/Userland/Utilities/usermod.cpp
+++ b/Userland/Utilities/usermod.cpp
@@ -57,6 +57,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     StringView shell;
     StringView gecos;
     StringView username;
+    Vector<gid_t> extra_gids;
 
     auto args_parser = Core::ArgsParser();
     args_parser.set_general_help("Modify a user account");
@@ -74,6 +75,21 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
             return gid.has_value();
         },
     });
+    args_parser.add_option(Core::ArgsParser::Option {
+        .argument_mode = Core::ArgsParser::OptionArgumentMode::Required,
+        .help_string = "Set the user's supplementary groups. Groups are specified with a comma-separated list. Group names or numbers may be used",
+        .long_name = "groups",
+        .short_name = 'G',
+        .value_name = "groups",
+        .accept_value = [&extra_gids](StringView comma_separated_groups) {
+            auto groups = comma_separated_groups.split_view(',');
+            for (auto group : groups) {
+                if (auto gid = group_string_to_gid(group); gid.has_value())
+                    extra_gids.append(gid.value());
+            }
+            return true;
+        },
+    });
     args_parser.add_option(lock, "Lock password", "lock", 'L');
     args_parser.add_option(unlock, "Unlock password", "unlock", 'U');
     args_parser.add_option(new_home_directory, "The user's new login directory", "home", 'd', "new-home");
@@ -162,6 +178,10 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
         target_account.set_gecos(gecos);
     }
 
+    if (!extra_gids.is_empty()) {
+        target_account.set_extra_gids(extra_gids);
+    }
+
     TRY(Core::System::pledge("stdio wpath rpath cpath fattr"));
 
     TRY(target_account.sync());