The ambitious Cape Town-based club made the announcement on their official Twitter account.
Majoro becomes the third Pirates player to join City during the transfer period after goalkeeper Samora Motloung and defender Tshepo Gumede also joined the Eric Tinkler-led side.
City have also added Ebrahim Seedat, Never Ngcuka, Shaquille Abrahams, Duncan Adonis, Robyn Johannes, Australian Matt Sim, as well as Austrian midfielder Roland Putsche to their squad.
Cape Town businessman John Comitis bought Mpumalanga Black Aces at the end of last season and renamed it Cape Town City FC after the club relocated to the Mother City.
— CapeTownCityFC (@CapeTownCityFC) 9 August 2016