Abou-Gabal, 24, has joined on a free transfer just one day after being released by ENPPI, where he played for several years.
Abou-Gabal becomes the second player to join Zamalek this summer after full-back Ahmed Fawzi had signed from Wadi Degla.
He was brought in after veteran keeper Mohamed Al-Akabawi had suddenly annulled his deal only days following his transfer from Arab Contractors.
Zamalek now have veteran Abdul-Wahed Al-Sayed, Mahmoud Abdul-Rahim 'Gennesh' and the newly-signed Abou-Gabal as first-team keepers among their ranks.