diff --git a/changelogs/fragments/9965-fix-duplicate-jsonify-payload-for-rocketchat-pre740.yml b/changelogs/fragments/9965-fix-duplicate-jsonify-payload-for-rocketchat-pre740.yml
new file mode 100644
index 0000000000..3364b4acc8
--- /dev/null
+++ b/changelogs/fragments/9965-fix-duplicate-jsonify-payload-for-rocketchat-pre740.yml
@@ -0,0 +1,2 @@
+minor_changes:
+  - rocketchat - fix duplicate JSON conversion for Rocket.Chat < 7.4.0 (https://github.com/ansible-collections/community.general/pull/9965).
diff --git a/plugins/modules/rocketchat.py b/plugins/modules/rocketchat.py
index 91192875dc..c09d75ace2 100644
--- a/plugins/modules/rocketchat.py
+++ b/plugins/modules/rocketchat.py
@@ -206,7 +206,7 @@ def build_payload_for_rocketchat(module, text, channel, username, icon_url, icon
 
     payload = module.jsonify(payload)
     if is_pre740:
-        payload = "payload=" + module.jsonify(payload)
+        payload = "payload=" + payload
     return payload