The wily 31-year-old nodded home in the 70th minute at Melbourne Rectangular Stadium, setting up a mouth-watering decider against Sydney FC next week and underlining his claim as Australian football's ultimate big-game player.
Winners in 2006-07, 2008-09 and 2014-15, the Kevin Muscat-coached Victory will bid for a record fourth A-League title.
But twice champions Sydney will be raging favourites to win a third title at home, having thrashed Perth Glory 3-0 in the first semi-final on Saturday after wrapping up the most dominant regular season in the league's history.
The sides will meet in a third Grand Final, with Sydney winning the first away in 2009-10 and Melbourne avenging the loss at home two years ago.
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The final score flattered John Aloisi's Roar, who were under siege throughout but let off the hook repeatedly by poor finishing from the home side.
It took a sumptuous, lofted cross from Tunisia midfielder Fahid Ben Khalfallah to break the deadlock and Berisha, the most prolific goal-scorer in the league's history, rose highest to hammer the ball home, notching his 20th goal of the season and 101st in Australian football.
"The most important are the finals so you make sure you're ready," said Berisha, the regular season's Golden Boot winner with Roar striker Jamie Maclaren.
"(Roar) are always very hard to play but I thought we'd been dominant ... We created a lot of chances, we were a little bit unlucky but I believed we deserved to win today."
(Editing by Amlan Chakraborty)
