It was a fourth straight win for Glory who have won 14 from 19 games this season for 46 points - nine ahead of the second placed Melbourne Victory.
They found little resistance from Brisbane at HBF Park on Saturday night despite the Roar improving in recent weeks.
Since a 5-0 loss to Victory, Brisbane had beaten Sydney FC, drawn with Western Sydney and Central Coast, and lost in a seven-goal thriller to Adelaide.
But this was a Roar devoid of fight and admittedly down on personnel headlined by the absence of striker Adam Taggart and suspended goalkeeper Jamie Young.
Glory took another significant step towards their first Premiers' Plate with the big win that was all set up with a commanding first half.
They were in control of the contest and it was inevitable their first goal came, which was a crisp strike from Jason Davidson in the 19th minute.
Then with his first touch of the game having come on to replace Ivan Franjic, Scott Neville put a cross right on point for Andy Keogh to head home.
Keogh added a second just on halftime, albeit controversially. He appeared offside when receiving the pass to tap in from Diego Castro, but it was given the all clear and Perth went in 3-0 up.
There was more Castro magic to start the second half when he coolly scored after a good cross into the box from Davidson in the 54th minute to make it 4-0.
Glory continued to attack and created a host more chances. While they couldn't capitalise to further ram home their dominance, the 4-0 scoreline sufficiently told the story of their control of the contest.
