Marc Janko scored a stunning long-range goal in the first half before Milos Dimitrijevic curled in a screamer of his own to hand a third straight loss to Mike Mulvey's side, who lacked ideas all night.
While Brisbane are now bottom of the table, Sydney are top after securing seven points from their opening three games.
When Janko broke the deadlock at Suncorp Stadium after 28 minutes, it was a moment of magic from the Austria international.
Roar goalkeeper Jamie Young attempted to clear the ball, but Janko got to it first and unleashed a tremendous left-footed effort into the empty net.
Not to be outdone, Dimitrijevic opened his account for the season in style as his curling, dipping effort sailed into the top corner following some neat interplay with Alex Brosque.
