The 24-year-old right-back failed to establish himself at Bucs during the 2016/17 season - after joining the club from Lamontville Golden Arrows in August, 2016.
Usuthu, who purchased 2016/17 National First Division (NFD) champions Thanda Royal Zulu's PSL status, have been busy in the current Transfer Window.
The KwaZulu-Natal giants have signed Sadate Ouro-Akoriko, Mhlengi Cele and Ayabulela Konqobe amongst others.
Sikhakhane, who hails from KwaZulu-Natal, made 14 appearances in all competitions for the Buccaneers last season.
He signed a long-term deal with Bucs when he joined the Soweto giants from Abafana Bes'thende.