Bruce Kamau scored twice in the space of four minutes as Western Sydney turned the game around in a hurry, putting the Wanderers on course for a win that would have lifted them up to third in the table.
However, the Mariners – who had taken the lead midway through the first half when Matt Simon converted a one-on-one opportunity with a chipped finish – levelled from the penalty spot.
Alou Kuol was caught by Keanu Baccus as they both went for a loose ball and, after a VAR check, captain Oliver Bozanic converted from 12 yards out in the 83rd minute.
Western Sydney has now only lost once in the past 11 meetings between the teams. The Wanderers looked on course for all three points thanks to Kamau, who scored multiple goals in an A-League game for the second time in his career.
The substitute made it 1-1 when turning in Thomas Aquilina's low cross, then quickly had the host ahead when he ended a driving run with a shot that took a deflection to sneak past Mark Birighitti in the visiting goal.