diff --git a/changelogs/fragments/diff-mode-firewall_rules.yml b/changelogs/fragments/diff-mode-firewall_rules.yml
new file mode 100644
index 00000000..b5ecf15a
--- /dev/null
+++ b/changelogs/fragments/diff-mode-firewall_rules.yml
@@ -0,0 +1,3 @@
+---
+major_changes:
+  - Support `diff mode <https://docs.ansible.com/ansible/latest/user_guide/playbooks_checkmode.html#using-diff-mode>` in ``vyos_firewall_rules``
diff --git a/plugins/module_utils/network/vyos/config/firewall_rules/firewall_rules.py b/plugins/module_utils/network/vyos/config/firewall_rules/firewall_rules.py
index 106b2b8b..53e1bfde 100644
--- a/plugins/module_utils/network/vyos/config/firewall_rules/firewall_rules.py
+++ b/plugins/module_utils/network/vyos/config/firewall_rules/firewall_rules.py
@@ -117,6 +117,17 @@ def execute_module(self):
             result["gathered"] = changed_firewall_rules_facts
 
         result["warnings"] = warnings
+
+        if self.state in self.ACTION_STATES and self._module._diff:
+            result["diff"] = {
+                "after": "\n".join(
+                    sorted(self.set_state(self._module.params["config"], {}))
+                ),
+                "before": "\n".join(
+                    sorted(self.set_state(existing_firewall_rules_facts, {}))
+                ),
+            }
+
         return result
 
     def set_config(self, existing_firewall_rules_facts):