Erick Mathoho made his first start this season for Chiefs along with the returning Reeve Frosler, as Pirates recalled Thulani Hlatshwayo who missed the win over Bloemfontein Celtic.
After a slow start by both sides, the match began to come alive with a glancing header in the area from Leonardo Castro forcing Pirates goalkeeper Richard Ofori to go down and collect.
Chiefs were forced to make a substitution midway through the first half after foot injury from Frosler immediately brought an end to his afternoon, with Siphelele Ntshangase getting a rare appearance.
The Amakhosi had a good chance to go ahead six minutes before halftime, but Thabang Monare dropped back to clear Daniel Cardoso's snap effort.
Chiefs should've taken the lead from a loose ball in the area by Ntshangase 12 minutes after the break, but the woodwork rescued the Sea Robbers.
Pirates went ahead a minute later when a surging run from Deon Hotto culminated with a shot which Daniel Akpeyi steered into the path of Fortune Makaringe, who tapped into an empty net.
Chiefs' miserable afternoon was compounded 12 minutes from time when Linda Mntambo beat the offside trap to collect Hotto's through ball for a composed finish.
The Amakhosi finished the match with ten players in added time when Mathoho got a second yellow card for pulling Zakhele Lepasa, as the Buccaneers marched to the final to play Bloemfontein Celtic.
Chiefs: Akpeyi, Frosler, Sasman, Cardoso, Mathoho, Akumu, Blom, Manyama, Parker, Billiat, Castro
Subs: Khune, Baccus, Moleko, Ngcobo, Ngezana, Ntshangase, Ntiya-Ntiya, Kambole, Lesako