De Villiers, who retired from international cricket in April last year, said the decision to join the Heat for the BBL was straight-forward.
On the other hand, Heat coach Darren Lehmann said he was over the moon to have the chance to work with de Villiers for the first time.
The former South Africa captain would be potentially playing six games as well as being available for the finals should the Heat qualify in the upcoming BBL edition.
De Villiers represented Proteas in 114 Tests, 228 ODIs and 78 T20Is in which he amassed 8765, 9577 and 1672 runs, respectively. He was a part of the Royal Challengers Bangalore in the last season of the Indian Premier League where he scored 442 runs at a strike rate of 154 including five 50-plus scores.