David Williams' fourth league goal of the campaign handed the visitors the lead but Aaron Mooy drew Wanderers level before half-time in Saturday's game.
Kewell, who had been out since the opening day with a neck injury, came off the bench for the final 18 minutes but Heart were denied a triumph that would have lifted them off the foot of the table.
There was an air of fortune about Williams' opener, which came after 38 minutes when his cross deceived goalkeeper Ante Covic and found the top corner.
The hosts responded promptly as Mooy, who had already spurned two good opportunities, fired home from the edge of the box.
Wanderers dominated the second half but efforts from Youssouf Hersi, Labinot Haliti, Mooy and Matthew Spiranovic all failed to breach Andrew Redmayne's goal.
Daniel McBreen's goal earned Central Coast a 1-0 triumph over Sydney FC.
A clever back-heel from the 36-year-old in the 26th minute ultimately proved the difference between the two sides.
The 2012-13 Golden Boot winner finished off a slick passing move started after the Mariners regained possession following a Joshua Rose shot on goal.
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