The host side was looking to put an end to a five-match winless run but had Elvis Kamsoba dismissed for two yellow cards inside the opening 32 minutes, the second for a studs-up challenge on Paulo Retre.
Bobo put Sydney in front 10 minutes later with a close-range finish into an empty net after Kosta Barbarouses got in behind and pulled the ball back into the six-yard box.
That was just the fifth time in the 2020-21 campaign Steve Corica's side had opened the scoring and they had another goal early in the second half through Barbarouses.
The New Zealand international, who spent two spells with Victory, took Anthony Caceres' throughball in his stride and fired across Matthew Acton into the far-left corner.
Sydney pushed for another and it arrived late on when VAR adjudged Dylan Ryan had fouled Ryan McGowan in the area, allowing substitute Alexander Baumjohann to step up and fired past Acton.
As well as winning six games on the spin against their rivals, Sydney has also now won 13 of the last 16 league encounters and are up to sixth in the A-League ladder, 14 points better off than bottom side Victory.