diff --git a/Makefile.am b/Makefile.am
index 1c1f5d84fd..8edd371ccd 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -380,6 +380,7 @@ MODULES =					\
   guix/scripts/fork.scm			\
   guix/scripts/fork/create.scm			\
   guix/scripts/fork/authenticate.scm			\
+  guix/scripts/fork/update.scm			\
   guix/scripts/graph.scm			\
   guix/scripts/weather.scm			\
   guix/scripts/container.scm			\
diff --git a/guix/scripts/fork.scm b/guix/scripts/fork.scm
index c5c7a59ba7..bf9c86e0aa 100644
--- a/guix/scripts/fork.scm
+++ b/guix/scripts/fork.scm
@@ -32,6 +32,8 @@ (define (show-help)
    create          set up a fork of Guix\n"))
   (display (G_ "\
    authenticate    authenticate a fork of Guix\n"))
+  (display (G_ "\
+   update          update a fork of Guix\n"))
   (newline)
   (display (G_ "
   -h, --help             display this help and exit"))
@@ -40,7 +42,7 @@ (define (show-help)
   (newline)
   (show-bug-report-information))
 
-(define %sub-commands '("create" "authenticate"))
+(define %sub-commands '("create" "authenticate" "update"))
 
 (define (resolve-sub-command name)
   (let ((module (resolve-interface
diff --git a/guix/scripts/fork/update.scm b/guix/scripts/fork/update.scm
new file mode 100644
index 0000000000..4223b9855c
--- /dev/null
+++ b/guix/scripts/fork/update.scm
@@ -0,0 +1,182 @@
+;;; GNU Guix --- Functional package management for GNU
+;;; Copyright © 2025 Tomas Volf <~@wolfsden.cz>
+;;; Copyright © 2025 45mg <45mg.writes@gmail.com>
+;;;
+;;; This file is part of GNU Guix.
+;;;
+;;; GNU Guix is free software; you can redistribute it and/or modify it
+;;; under the terms of the GNU General Public License as published by
+;;; the Free Software Foundation; either version 3 of the License, or (at
+;;; your option) any later version.
+;;;
+;;; GNU Guix is distributed in the hope that it will be useful, but
+;;; WITHOUT ANY WARRANTY; without even the implied warranty of
+;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;;; GNU General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU General Public License
+;;; along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.
+
+(define-module (guix scripts fork update)
+  #:use-module (guix scripts fork authenticate)
+  #:use-module (git repository)
+  #:use-module (git structs)
+  #:use-module (git config)
+  #:use-module (guix ui)
+  #:use-module (guix scripts)
+  #:use-module ((guix utils) #:select (invoke/stdout))  ;TODO move invoke/stdout to (guix build utils)
+  #:use-module (guix build utils)
+  #:use-module (guix channels)
+  #:use-module (ice-9 exceptions)
+  #:use-module (ice-9 match)
+  #:use-module (ice-9 popen)
+  #:use-module (ice-9 pretty-print)
+  #:use-module (ice-9 string-fun)
+  #:use-module (ice-9 textual-ports)
+  #:use-module (srfi srfi-1)
+  #:use-module (srfi srfi-13)
+  #:use-module (srfi srfi-26)
+  #:use-module (srfi srfi-37)
+  #:use-module (srfi srfi-71)
+  #:export (guix-fork-update))
+
+;;; Commentary:
+;;;
+;;; Update a fork of Guix created via `guix fork create` and authenticated via
+;;; `guix fork authenticate`, by applying new commits from the upstream branch
+;;; onto it.
+;;;
+;;; Code:
+
+(define %options
+  ;; Specifications of the command-line options.
+  (list (option '(#\h "help") #f #f
+                (lambda args
+                  (show-help)
+                  (exit 0)))
+        (option '(#\V "version") #f #f
+                (lambda args
+                  (show-version-and-exit "guix fork create")))
+
+        (option '( "fork-branch") #t #f
+                (lambda (opt name arg result)
+                  (alist-cons 'fork-branch-name arg result)))
+        (option '(#\r "repository") #t #f
+                (lambda (opt name arg result)
+                  (alist-cons 'directory arg result)))))
+
+(define %default-options
+  '())
+
+(define %usage
+  (G_ "Usage: guix fork update [OPTIONS...]
+Pull into this Guix fork's configured upstream branch, then apply new commits
+onto the current branch.
+
+  -r, --repository=DIRECTORY
+                         Act in the Git repository in DIRECTORY
+      --fork-branch=BRANCH
+                         Apply new commits onto BRANCH instead of the current
+                         branch
+
+  -h, --help             display this help and exit
+  -V, --version          display version information and exit
+"))
+
+(define (show-help)
+  (display %usage)
+  (newline)
+  (show-bug-report-information))
+
+(define (missing-arguments)
+    (leave (G_ "wrong number of arguments; \
+required ~%")))
+
+
+;;;
+;;; Entry point.
+;;;
+
+(define (guix-fork-update . args)
+
+  (define options
+    (parse-command-line args %options (list %default-options)
+                        #:build-options? #f))
+
+  (define (command-line-arguments lst)
+    (reverse (filter-map (match-lambda
+                           (('argument . arg) arg)
+                           (_ #f))
+                         lst)))
+
+  (define-syntax invoke-git
+    (lambda (x)
+      (syntax-case x ()
+        ((_ args ...)
+         #`(invoke "git" "-C" #,(datum->syntax x 'directory) args ...)))))
+
+  (define-syntax invoke-git/stdout
+    (lambda (x)
+      (syntax-case x ()
+        ((_ args ...)
+         #`(string-trim-right
+            (invoke/stdout "git" "-C" #,(datum->syntax x 'directory) args ...))))))
+
+  (with-error-handling
+    (let* ((directory (or (assoc-ref options 'directory) "."))
+           (current-branch-name (invoke-git/stdout
+                                 "branch"
+                                 "--show-current"))
+           (current-head-location (invoke-git/stdout
+                                   "rev-parse"
+                                   "HEAD"))
+           (fork-branch-name (or (assoc-ref options 'fork-branch-name)
+                                 (if (string= current-branch-name "")
+                                     (leave (G_ "no current branch and --fork-branch not given"))
+                                     current-branch-name)))
+
+           (repository (repository-open directory))
+           (upstream-branch-name introduction-commit introduction-signer
+                                 (if (fork-configured? repository)
+                                     (fork-configured-introduction
+                                      (repository-open directory))
+                                     (leave (G_ "fork not fully configured.
+(Did you remember to run `guix fork authenticate` first?)%~"))))
+           (upstream-branch-commit
+            (invoke-git/stdout "rev-parse" upstream-branch-name))
+           (new-upstream-branch-commit "")
+           (config (repository-config repository))
+           (signing-key
+            (or
+             (catch 'git-error
+               (lambda ()
+                 (config-entry-value
+                  (config-get-entry config "user.signingkey")))
+               (const #f))
+             (begin
+               (info (G_ "user.signingkey not set for this repository.~%"))
+               (info (G_ "Will attempt to sign commits with fork introduction key.~%"))
+               introduction-signer))))
+
+      (info (G_ "Pulling into '~a'...~%") upstream-branch-name)
+      (invoke-git "switch" upstream-branch-name)
+      (invoke-git "pull")
+      (set! new-upstream-branch-commit
+            (invoke-git/stdout "rev-parse" upstream-branch-name))
+
+      (info (G_ "Rebasing commits from '~a' to '~a' onto fork branch '~a'...~%")
+            upstream-branch-commit
+            new-upstream-branch-commit
+            fork-branch-name)
+      (invoke-git "rebase" "--rebase-merges"
+                  (string-append "--gpg-sign=" signing-key)
+                  fork-branch-name new-upstream-branch-commit)
+
+      (info (G_ "Resetting fork branch '~a' to latest rebased commit...~%")
+            fork-branch-name)
+      (invoke-git "branch" "--force" fork-branch-name "HEAD")
+
+      (invoke-git "checkout" (or current-branch-name current-head-location))
+
+      (info (G_ "Successfully updated Guix fork in ~a~%")
+            directory))))
