With the game seemingly headed for a goalless draw, up stepped Mokate to head home the only goal of the evening with the cross coming in from Deolin Mekoa.
The win means Maritzburg rise to 36 points as they jump from eighth to seventh on the league table.
For Ajax, they remain on 37 points in sixth spot.
Just after the 20 minute mark, Ajax midfielder Keagan Dolly reeled off a shot but it was blocked by Maritzburg player Philani Zulu. Franklin Cale sent in the resultant corner and Ntuthuko Mabaso cleared the danger.
Moments later Ajax were on the prowl again. This time Abbubaker Mobara was on hand with the shot, but Maritzburg keeper Shuaib Walters was up to the task and tipped the ball away for a corner.
Dolly was involved again just before the half-hour mark with a shot, but Walters again had it covered as he made the save.
