diff --git a/CHANGES b/CHANGES
index d34034f8ca2..f3b1ccb4861 100644
--- a/CHANGES
+++ b/CHANGES
@@ -22,6 +22,7 @@ Features added
   this behavior with the ``--respect-module-all`` switch.
 * #9800: extlinks: Emit warning if a hardcoded link is replaceable
   by an extlink, suggesting a replacement.
+* #9961: html: Support nested <kbd> HTML elements in other HTML builders
 * #9815: html theme: Wrap sidebar components in div to allow customizing their
   layout via CSS
 * #9899: py domain: Allows to specify cross-reference specifier (``.`` and
diff --git a/sphinx/builders/html/transforms.py b/sphinx/builders/html/transforms.py
index cb9af5f2895..338c87b7f99 100644
--- a/sphinx/builders/html/transforms.py
+++ b/sphinx/builders/html/transforms.py
@@ -36,7 +36,7 @@ class KeyboardTransform(SphinxPostTransform):
                 x
     """
     default_priority = 400
-    builders = ('html',)
+    formats = ('html',)
     pattern = re.compile(r'(?<=.)(-|\+|\^|\s+)(?=.)')
     multiwords_keys = (('caps', 'lock'),
                        ('page' 'down'),