diff --git a/changelogs/fragments/reboot-unicode-string.yaml b/changelogs/fragments/reboot-unicode-string.yaml
new file mode 100644
index 00000000000..5ac36b924bd
--- /dev/null
+++ b/changelogs/fragments/reboot-unicode-string.yaml
@@ -0,0 +1,3 @@
+bugfixes:
+  - reboot - use unicode instead of bytes for stdout and stderr to match the
+    type returned from low_level_execute()
diff --git a/lib/ansible/plugins/action/reboot.py b/lib/ansible/plugins/action/reboot.py
index 4dd90149a50..a440ff3875b 100644
--- a/lib/ansible/plugins/action/reboot.py
+++ b/lib/ansible/plugins/action/reboot.py
@@ -94,8 +94,8 @@ class ActionModule(ActionBase):
         return reboot_command
 
     def get_system_boot_time(self):
-        stdout = b''
-        stderr = b''
+        stdout = u''
+        stderr = u''
         command_result = self._low_level_execute_command(self.DEFAULT_BOOT_TIME_COMMAND, sudoable=self.DEFAULT_SUDOABLE)
 
         # For single board computers, e.g., Raspberry Pi, that lack a real time clock and are using fake-hwclock