It is understood that the deal has been sealed as the 31-year-old joined his new teammates on Wednesday when The Birds resumed pre-season training in Bedfordview.
Mahoa, who is an Absa Premiership champion from his time at SuperSport United, has secured a two-year deal.
Swallows are re-building their squad following the exit of Giorgi Nergadze and Asavela Mbekile who moved to Bidvest Wits and Mamelodi Sundowns respectively.
Mahoa is one of the longest serving left backs in the country and provides reliable cover in a key position on the left flank.
Meanwhile Swallows have also signed Philani Cele and Lucky Baloyi from Kaizer Chiefs. Both players were at training yesterday.