diff --git a/docs/changes.rst b/docs/changes.rst
index 955a38a2e32c..a4d3eb11d896 100644
--- a/docs/changes.rst
+++ b/docs/changes.rst
@@ -5,6 +5,7 @@ Weblate 2026.7
 
 .. rubric:: New features
 
+* Added the :ref:`check-accelerators` quality check, which verifies that accelerator keys are used consistently between the source and the translation. Enable it with the ``accelerators`` flag.
 * Added :ref:`mt-mistral` machinery integration for Mistral LLM automatic suggestions.
 
 .. rubric:: Improvements
diff --git a/docs/snippets/check-flags-autogenerated.rst b/docs/snippets/check-flags-autogenerated.rst
index 4d60bdb64599..d18c2e38ba4c 100644
--- a/docs/snippets/check-flags-autogenerated.rst
+++ b/docs/snippets/check-flags-autogenerated.rst
@@ -47,6 +47,8 @@
 .. AUTOGENERATED START: check-flags-enables
 .. This section is automatically generated by `./manage.py list_checks`. Do not edit manually.
 
+``accelerators``
+    Enables the :ref:`check-accelerators` quality check.
 ``bbcode-text``
     Treat a text as an Bulletin Board Code (BBCode) document, affects :ref:`check-same`.
     Enables the :ref:`check-bbcode` quality check.
@@ -150,6 +152,8 @@
 .. AUTOGENERATED START: check-flags-ignores
 .. This section is automatically generated by `./manage.py list_checks`. Do not edit manually.
 
+``ignore-accelerators``
+    Skip the :ref:`check-accelerators` quality check.
 ``ignore-bbcode``
     Skip the :ref:`check-bbcode` quality check.
 ``ignore-xml-chars-around-tags``
diff --git a/docs/snippets/checks-autogenerated.rst b/docs/snippets/checks-autogenerated.rst
index 051650d62041..5fac9c7b8ed5 100644
--- a/docs/snippets/checks-autogenerated.rst
+++ b/docs/snippets/checks-autogenerated.rst
@@ -4,6 +4,40 @@ Translation checks
 Executed upon every translation change, helping translators maintain
 good quality translations.
 
+.. AUTOGENERATED START: check-accelerators
+.. This section is automatically generated by `./manage.py list_checks`. Do not edit manually.
+
+.. _check-accelerators:
+
+Accelerator key
+~~~~~~~~~~~~~~~
+
+.. versionadded:: 2026.7
+
+:Summary: Source and translation contain inconsistent accelerator keys.
+:Scope: translated strings
+:Check class: ``weblate.checks.chars.AcceleratorKeyCheck``
+:Check identifier: ``accelerators``
+:Trigger: This check needs to be enabled using a flag.
+:Flag to enable: ``accelerators``
+:Flag to ignore: ``ignore-accelerators``
+
+.. AUTOGENERATED END: check-accelerators
+
+Accelerator keys (also known as mnemonics) let users trigger a UI action from
+the keyboard. They are marked in the string by a single character, typically
+``&`` (Qt, Windows) or ``_`` (GTK). Literal marker characters can usually be
+escaped (for example ``&&`` in Qt/Windows and ``__`` in GTK) and are ignored by
+this check, as are HTML entities such as ``&``. This check verifies that the
+source and the translation contain the same number of accelerator keys, and that
+the translation does not contain more than one.
+
+.. note::
+
+    A string such as ``Walter & Sons`` might be translated without the
+    ampersand and trigger a false positive. Use the ``ignore-accelerators``
+    flag to skip the check for such strings.
+
 .. AUTOGENERATED START: check-bbcode
 .. This section is automatically generated by `./manage.py list_checks`. Do not edit manually.
 
diff --git a/weblate/checks/chars.py b/weblate/checks/chars.py
index 0629c34ffafd..421cdc9f0c8e 100644
--- a/weblate/checks/chars.py
+++ b/weblate/checks/chars.py
@@ -41,6 +41,39 @@
 INTERROBANGS = ("?!", "!?", "؟!", "!؟", "？！", "！？", "⁈", "⁉")
 
 
+class AcceleratorKeyCheck(TargetCheck):
+    """Check for inconsistent accelerator keys."""
+
+    check_id = "accelerators"
+    name = gettext_lazy("Accelerator key")
+    description = gettext_lazy(
+        "Source and translation contain inconsistent accelerator keys."
+    )
+    default_disabled = True
+    version_added = "2026.7"
+
+    def _count_accelerators(self, text: str, key: str) -> int:
+        # HTML/XML entities start with '&' but are not accelerator markers.
+        if key == "&":
+            text = strip_entities(text)
+            # Qt/Windows escape a literal ampersand as "&&".
+            text = text.replace("&&", "")
+        elif key == "_":
+            # GTK escapes a literal underscore as "__".
+            text = text.replace("__", "")
+        return text.count(key)
+
+    def _check_accelerator(self, source: str, target: str, key: str) -> bool:
+        src_count = self._count_accelerators(source, key)
+        tgt_count = self._count_accelerators(target, key)
+        return tgt_count > 1 or src_count != tgt_count
+
+    def check_single(self, source: str, target: str, unit: Unit) -> bool:
+        return self._check_accelerator(source, target, "&") or self._check_accelerator(
+            source, target, "_"
+        )
+
+
 class BeginNewlineCheck(TargetCheck):
     """Check for newlines at beginning."""
 
diff --git a/weblate/checks/defaults.py b/weblate/checks/defaults.py
index ab5352c5ae4f..ca7c946c205c 100644
--- a/weblate/checks/defaults.py
+++ b/weblate/checks/defaults.py
@@ -6,6 +6,7 @@
 
 DEFAULT_CHECK_LIST: tuple[str, ...] = (
     "weblate.checks.same.SameCheck",
+    "weblate.checks.chars.AcceleratorKeyCheck",
     "weblate.checks.chars.BeginNewlineCheck",
     "weblate.checks.chars.EndNewlineCheck",
     "weblate.checks.chars.BeginSpaceCheck",
diff --git a/weblate/checks/tests/test_chars_checks.py b/weblate/checks/tests/test_chars_checks.py
index 6508ca6f392a..8c87d25edd79 100644
--- a/weblate/checks/tests/test_chars_checks.py
+++ b/weblate/checks/tests/test_chars_checks.py
@@ -7,6 +7,7 @@
 from django.test import SimpleTestCase
 
 from weblate.checks.chars import (
+    AcceleratorKeyCheck,
     BeginNewlineCheck,
     BeginSpaceCheck,
     DoubleSpaceCheck,
@@ -32,6 +33,39 @@
 from weblate.trans.tests.factories import make_check, make_unit
 
 
+class AcceleratorKeyCheckTest(CheckTestCase):
+    check = AcceleratorKeyCheck()
+
+    def setUp(self) -> None:
+        super().setUp()
+        self.test_good_matching = ("&File", "&File", "accelerators")
+        self.test_good_none = ("File", "File", "accelerators")
+        self.test_good_flag = ("&File", "File", "")
+        self.test_failure_1 = ("&File", "File", "accelerators")
+        self.test_failure_2 = ("File", "&File", "accelerators")
+        self.test_failure_3 = ("&File", "&File &Edit", "accelerators")
+
+    def test_underscore_accelerator(self) -> None:
+        self.do_test(False, ("_File", "_File", "accelerators"))
+        self.do_test(True, ("_File", "File", "accelerators"))
+        self.do_test(True, ("File", "_File", "accelerators"))
+
+    def test_literal_ampersand(self) -> None:
+        # A literal ampersand present in both source and translation should not trigger this check.
+        self.do_test(False, ("Walter & Sons", "Walter & Sons", "accelerators"))
+        # Escaped/literal ampersands (Qt/Windows "&&") should not count as accelerators.
+        self.do_test(False, ("Save && Exit", "Save && Exit", "accelerators"))
+        # HTML entities should not be treated as accelerators.
+        self.do_test(False, ("Fish & Chips", "Fish & Chips", "accelerators"))
+        self.do_test(False, ("A & B & C", "A & B & C", "accelerators"))
+
+    def test_escaped_underscore(self) -> None:
+        # Escaped/literal underscores (GTK "__") should not count as accelerators.
+        self.do_test(False, ("__File", "__File", "accelerators"))
+        # "___" is commonly used for a literal underscore plus an accelerator marker.
+        self.do_test(False, ("___File", "___File", "accelerators"))
+
+
 class BeginNewlineCheckTest(CheckTestCase):
     check = BeginNewlineCheck()
 
diff --git a/weblate/settings_example.py b/weblate/settings_example.py
index 2f77f296f77f..805c49d630e0 100644
--- a/weblate/settings_example.py
+++ b/weblate/settings_example.py
@@ -728,6 +728,7 @@
 # List of quality checks
 # CHECK_LIST = (
 #     "weblate.checks.same.SameCheck",
+#     "weblate.checks.chars.AcceleratorKeyCheck",
 #     "weblate.checks.chars.BeginNewlineCheck",
 #     "weblate.checks.chars.EndNewlineCheck",
 #     "weblate.checks.chars.BeginSpaceCheck",