Seedat, 23, has signed on the dotted line after convincing coach Eric Tinkler during a trial period over the last two weeks.
Club owner John Comitis has promised to bolster the ranks with talent sourced from Cape Town, and has started doing just that.
The other players added to the City ranks are Never Ngcuka, Shaquille Abrahams and Duncan Adonis. They all join from National First Division outfit FC Cape Town where Comitis spent time as a director.
Abrahams and Adonis are both teenagers at 19 and 17 years of age respectively while Ngcuka is 20.