diff --git a/changelogs/fragments/57711-To_resolve_NoneType_error_in_aci_l3out.yaml b/changelogs/fragments/57711-To_resolve_NoneType_error_in_aci_l3out.yaml
new file mode 100644
index 0000000000..3cc1596dac
--- /dev/null
+++ b/changelogs/fragments/57711-To_resolve_NoneType_error_in_aci_l3out.yaml
@@ -0,0 +1,3 @@
+bugfixes:
+  - To resolve NoneType error as it was missing NoneType check for l3protocol param in aci_l3out.
+    (https://github.com/ansible/ansible/pull/58618).
diff --git a/lib/ansible/modules/network/aci/aci_l3out.py b/lib/ansible/modules/network/aci/aci_l3out.py
index cfe2480c6f..ab8b7d07ea 100644
--- a/lib/ansible/modules/network/aci/aci_l3out.py
+++ b/lib/ansible/modules/network/aci/aci_l3out.py
@@ -280,10 +280,11 @@ def main():
     state = module.params['state']
     tenant = module.params['tenant']
 
-    if 'eigrp' in l3protocol and asn is None:
-        module.fail_json(msg="Parameter 'asn' is required when l3protocol is 'eigrp'")
-    if 'eigrp' not in l3protocol and asn is not None:
-        module.warn("Parameter 'asn' is only applicable when l3protocol is 'eigrp'. The ASN will be ignored")
+    if l3protocol:
+        if 'eigrp' in l3protocol and asn is None:
+            module.fail_json(msg="Parameter 'asn' is required when l3protocol is 'eigrp'")
+        if 'eigrp' not in l3protocol and asn is not None:
+            module.warn("Parameter 'asn' is only applicable when l3protocol is 'eigrp'. The ASN will be ignored")
 
     enforce_ctrl = ''
     if enforceRtctrl is not None: