According to the player's new manager Godfrey Mushanganyisi, the former Jomo Cosmos defender terminated his contract with Bucks after an agreement was reached between the parties.
In January Zulu left Bidvest Wits just seven months into his three-and-a-half-year contract, before spending only four months at Chippa United where he managed just four starts.
The 27-year-old had a trial with Platinum Stars before the start of the season, but he was not successful.
"Zulu has signed with the Lions of the North as he terminated his contract with Mthatha Bucks," Mushanganyisi tells KickOff.com.
Highlands boss Brad Kaftel confirmed the player's capture.
"Yes we have signed him. We have an option as well, so it could be two-and-a-half-years. So it's this season plus two more," Kaftel tells KickOff.com.