The Matildas star scored stunning goal to lift Perth to a 3-2 win over champions City in an action-packed encounter at AAMI Park.
Rosie Sutton scored the opener for the visitors was cancelled out by a flying volley from City's Jess Fishlock.
An Aivi Luik's strike midway through the second half put the hosts up but Kerr scored twice within seven minutes to put her side up after missing a number of chances in the first.
The league's top scorer extended her tally to seven goals with a curling shot that rebounded off the far post to seal the result, continuing a stunning reversal of fortunes for City who have now lost three matches straight, after previously going 18 games undefeated last season.
"We really wanted to get this win," Kerr said. "It (the comeback) shows how strong our team are and the team morale we have.
"We are putting in a great team effort ever week with everyone doing their job and that makes it easier for Rosie (Sutton) and myself."
Perth now sit a point clear of second-placed Sydney FC who opened the round on Friday with a hard-fought 1-0 win over Brisbane Roar.
Western Sydney Wanderers kept their semi-final hopes alive on Monday with their 2-1 comeback win over Newcastle Jets.