Egypt forward Amr Zaki fired past keeper Ahmed Fawzi midway through the first-half to score his second successive goal for Zamalek.
Fellow striker Abdul-Halim Ali ended his goal-drought and sealed the win just three minutes from the break
The win placed Zamalek first with six points from three games, leading Petrojet and Ismaili on goal difference.
International defender Medhat Abdul-Hadi featured for the first time against a Zamalek side that he captained for several years after signing for Petrojet in the close season.
Petrojet, who kicked-off the game splitting the first spot with Ismaili, began the game in style and laid siege to Zamalek's areas for the first ten minutes.
But Zamalek restored form quickly as Tamer Abdul-Hamid and Alaa Abdul-Ghani controlled the rhythm in the midfield while Walid Abdul-Latif, who replaced Hazem Emam as a playmaker, played a deep role behind the striking duo.
The home side grabbed the lead in the 28th minute after several passes in the midfield ended at Abdul-Hamid just before Petrojet's area.
Abdul-Hamid slipped a defense-splitting pass to the darting Zaki who outpaced marker Abdul-Hadi and sent a first-time bullet into the back of the net.
Two minutes later, Mahmoud Abdul-Hakim headed past Zamalek keeper Mohamed Abdul-Monsef but he was flagged for offside.
In the 42nd minute, Abdul-Latif went face-to-face with Fawzi but instead of shooting, he crossed to the unchallenged Ali who enjoyed an easy tap-in.
Petrojet coach Mokhtar Mokhtar fielded veteran strikers Alaa Ibrahim and Khaled Bibo after the break in a bid to narrow the gap but Zamalek managed to hold on to their victory.