The veteran striker is 36 today and was playing his 700th senior match and he celebrated by scoring with a fine, low shot in the 47th minute following a slide-rule pass by Paul Boertien.
In the first half slick-moving Carlisle had been much the better side, with Walsall making a string of unforced errors, and being out-played in midfield.
It was no surprise when the Cumbrians took a 19th-minute lead. Talented midfielder Simon Hackney split a static Walsall defence with an excellent pass for Kevin Gall to provide an equally good finish, leaving keeper Clayton Ince no chance of saving.
Prior to that Gall might easily have had other goals and very little was seen of the Walsall attack, apart from in the 17th minute when Portuguese striker Carlos Carneiro and winger Paul Hall created a chance for Daniel Fox to head over.
Mooney's early goal in the second half provided the spark that put Walsall on top and the veteran striker forced a double save from Keiren Westwood in the 50th minute.
Ince made a good save from Danny Graham in the 63rd minute, but Walsall had a great chance nine minutes later, only for Carneiro to meet Fox's cross with a tame header.
Four minutes later, with play swinging from end to end, Jeff Smith had a 25-yard shot tipped over by Ince and, with three minutes to go, former Walsall full-back Zigor Aranalde, having a good game for the Cumbrians, saw a deflected shot taken by the home keeper.