The Citizens have snapped up 19-year-old Groeneveld on a five-year deal following the end of his spell at Belgium's Standard Liege.
The Kimberely-born centre-back has been based in Belgium since the age of 4, and has previously represented their under-18 national team.
However, the teenager was last year called up to Amajita during the U-20 AFCON qualifiers but was forced to withdraw due to an expired SA passport.
Most notably, Groeneveld also underwent a trial at Premier League giants Manchester United and Arsenal back in May 2016, before eventually earning a professional contract at Liege a month later.
Though he has signed outside of the transfer window, City are able to register him immediately after he acquired amateur status earlier this year, having played for Liege's Under-21 side.