The two-time Asian champions clinched in continent's final eight for the third time in the past four seasons, while Piroozi's poor ACL run of results continued
Morrocan attacker Abdelghani Faouzi had a big influence on the game, winning a first-half penalty converted by Naif Hazazi and netted one himself on the stroke of half-time, before Abdoh Autef sealed their passage into the final eight with an 88th-minute strike.
Despite the scoreline, Persepolis gave Al Ittihad plenty of worries throughout the 90 minutes, however the Tigers proved the better side, particularly in the final third.
Persepolis keeper Asmir Avdukic had to be alert to deny Hazazi on three minutes, before making another stop from Egyptian Hosny Abd Rabo shortly after.
Piroozi's Libya international Eamon Zayed had a wonderful chance to put the visitors ahead on 15 minutes but his effort was well saved by Tigers keeper Mabrouk Zayed.
Eventually Al Ittihad grabbed the lead when Sheys Rezaei committed a foul on Faouzi inside the box, allowing Hazazi to score his fifth goal of this season's ACL from the spot.
Ten minutes later the Saudi club, who reached the semi-finals in 2011, doubled their lead when the Persepolis defence hesitated allowing Autef to set up Faouzi for 2-0.
Avdukic remained busy after the break, saving from Faouzi's effort before seeing substitute Fabrice N'Guessi Ondama's strike hit the woodwork.
Zayed almost hauled Persepolis back into the contest on 84 minutes when his header hit the crossbar, but Autef settled the match on 88 minutes after pouncing on a rebound when Mohammed Abousaban's free-kick had cannoned back off the woodwork.