Ivan Franjic's second-half goal gave Perth a 1-0 home victory over Newcastle Jets which earned Glory the A-League Premiers' Plate.
Sydney FC's failure to win the Sydney derby the previous day meant Tony Popovic's team had the chance to clinch their maiden premiership with a win in front of their own fans at HBF Park.
Franjic scored midway through the second half to deliver the club's first piece of silverware since they won the NSL championship in 2004, while they will also get a place in next season's Asian Champions League.
Newcastle's defeat ended their hopes of making the Finals Series, with the top six now set ahead of the final two rounds of the regular season.
The Jets gave Perth two early scares, first when striker Roy O'Donovan fired an audacious 33-metre dipping volley that looped over keeper Liam Reddy, but crashed against the crossbar.
O'Donovan was then denied a goal when, after latching onto Ivan Vujica's cross to send the ball home, referee Kurt Ams sent the decision to the VAR and replays showed the Irishman had been slightly offside.
Andy Keogh thumped a shot against the Jets bar from close range five minutes before the break as he met Joel Chianese's low cross from the right.
Perth, who saw midfielder Juande limp off with a knee injury on the half-hour mark, were denied a first-half penalty by the VAR and had goals ruled out for offside twice in the space of four minutes in the second half.
Franjic finally broke the deadlock when he latched onto a superb through pass from Diego Costa and drilled the ball through the legs of keeper Glen Moss.
The Glory are 2/1 to win their next game against Sydney FC, who are 11/8, with the draw 9/4.
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