diff --git a/changelogs/fragments/66929-pmrun-quote-entire-success-command-string.yml b/changelogs/fragments/66929-pmrun-quote-entire-success-command-string.yml
new file mode 100644
index 00000000000..769a5d1b51c
--- /dev/null
+++ b/changelogs/fragments/66929-pmrun-quote-entire-success-command-string.yml
@@ -0,0 +1,2 @@
+bugfixes:
+  - pmrun plugin - The success_command string was no longer quoted. This caused unusual use-cases like ``become_flags=su - root -c`` to fail.
diff --git a/lib/ansible/plugins/become/pmrun.py b/lib/ansible/plugins/become/pmrun.py
index 023cf408ba3..070352493d6 100644
--- a/lib/ansible/plugins/become/pmrun.py
+++ b/lib/ansible/plugins/become/pmrun.py
@@ -57,6 +57,7 @@ DOCUMENTATION = """
 """
 
 from ansible.plugins.become import BecomeBase
+from ansible.module_utils.six.moves import shlex_quote
 
 
 class BecomeModule(BecomeBase):
@@ -72,4 +73,4 @@ class BecomeModule(BecomeBase):
 
         become = self.get_option('become_exe') or self.name
         flags = self.get_option('become_flags') or ''
-        return '%s %s %s' % (become, flags, self._build_success_command(cmd, shell))
+        return '%s %s %s' % (become, flags, shlex_quote(self._build_success_command(cmd, shell)))