Played in by Matthew Grimaldi, Keegan Jelacic gave the Victory the lead after just 103 seconds at Jubilee Stadium on Wednesday night, before Jordan Courtney-Perkins inadvertently turned a Charles Nduka cutback into his own net 61 minutes in to provide a two-goal cushion.
The A-League Men powers, who advanced to a record-equalling fourth decider, will now await the victors of next Tuesday's semi between NPL Victoria outfit South and NPL Queensland side Lions FC.
Not invited into the newly created A-League after the collapse of the NSL, four-time Australian champions South Melbourne haven't faced the Victory in competitive play in the two decades since, with a clash between the two the biggest untapped rivalry in Australian football.
"It's amazing, anytime you get a chance to get some silverware you have to try and take it," defender Tom Lockyer told Paramount+.
"I said to the lads before the game, you know, some people go their whole careers without getting a trophy and we're in an amazing opportunity now to go into the final."
Stung by Jelacic's early strike, Sydney dominated possession throughout the contest but struggled to fashion consistent looks on goal and were ultimately out-shot by the visitors.
Sydney thought they should have had a penalty in the 23rd minute when keeper Jack Duncan arrived late and took out Takahiro Sekine as he headed towards goal, but referee Muhammad Taqi waved away what appeared to be a clear spot kick.
The Singaporean official and his team had been flown in by Football Australia amid ongoing strike action by Australia's elite referees over a contractual dispute.
New signing Oriola Sunday and skipper Rhyan Grant – who had escaped a flag despite replays showing he had strayed offside – then both headed wide for Sydney just before halftime.
And their imprecision was punished when N'Duka got into the area and forced Courtney-Perkins into a telling error, making it four wins in four for new Victory boss Giovanni Savarese.
