The result eased the pressure on under-fire coach Frank Farina as Sydney halted their slide down the table courtesy of strikes from Ranko Despotovic and Terry Antonis.
Rostyn Griffiths responded for Perth, who are now four without a win, but the visitors missed the chance to leapfrog Sydney in the table, even after Aaron Calver's late dismissal.
A run of just one win in nine had left Farina with some questions to answer, but Despotovic handed the hosts the ideal start, turning home Alessandro Del Piero's assist with 17 minutes gone.
The crowd were treated to an odd spectacle on the half-hour mark when the Glory won an indirect free-kick on the edge of the six-yard box, with the entire Sydney team lining up on the goalline before charging down Shane Smeltz's effort.
Having survived that scare, Antonis doubled Sydney's lead in the 64th minute with a fine curling effort.
Griffiths' header reduced the deficit three minutes later and Calver picked up his second booking in the dying moments, but the home side held on for three points.
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