Two goals in the second half from Eric Mathoho and new signing Lewis Macha sealed the victory for the Glamour Boys.
Amakhosi dominated much of the possession and made more attacks in the first half, but had nothing to show for it.
Chiefs began the second half from where they left off, keeping the ball and pushing forward, but none of their efforts turned into a goal.
It was Mathoho who got the crucial goal for Chiefs, when he benefited from a rebound shot from Bernard Parker, which struck the post and met the lanky defender inside and he calmly put the ball into an open net in the 58th.
Pirates started gelling well together with the introduction of Riyaad Norodien. The former Ajax Cape Town players almost got an equaliser for Bucs, but his effort went wide.
Amakhosi sealed the victory when new signing Macha introduced himself to South African football with a powerful header from a William Twala cross in injury time to make it 2-0 for Chiefs.
The competition which allows the supporters of both clubs to pick up the first XI and make substitutions during the match, has been dominated by the Buccaneers in recent years, with the side having won it four times, while Chiefs have only won it twice.