The Sky Blues, who had been winless in five matches, produced a stellar attacking display in the first half to take a three-goal lead.
The Sky Blues scored again early in the second half to kill off the match as a contest and were able to go through the motions against a hapless Victory side to consolidate their position in the top six.
Sydney made its attacking intentions clear from the start and Del Piero saw his bold chip just miss the bar after only two minutes' play.
Sydney was looking sharp and after surviving a mini-scare when Kosta Barbarouses shot timidly from a good position it took the lead in the 11th minute when striker Ranko Despotovic ran on to a long pass from Terry McFlynn, took a touch and found the far corner of the net with a low shot to stun the home crowd.
Melbourne could not contain Sydney's cohesive midfield and the visitor was awarded a penalty in the 18th minute when in-form Del Piero served Despotovic with another long ball but the striker was manhandled by Adrian Leijer and the Italian coolly slotted home the resultant spot kick.
Sydney's evening got even better when Sebastian Ryall went on a jinking run that took him past three defenders and he found the net with a cheeky shot from the outside of his right boot to put the Sky Blues three up.
Leijer was then taken off on a stretcher after a head clash and he was replaced by Jason Geria.
The first half ended with Sydney well on top and the Victory players booed off the field.
Victory brought on Tom Rogic at the start of the second half and made inroads into Sydney's defence.
But it was caught napping in the 54th minutes when Despotovic served the unmarked Del Piero and the Italian had no difficulty planting the ball in the net.
Sydney was in absolute control for the rest of the match and missed several chances to further punish a demoralised opponent before substitute Nick Carle completed the humiliation.