The Buccaneers took control of possession early on in the clash and kept Gallants on the back foot as they pinned them inside their own half.
Ndabayithetwa Ndlondlo threatened to score from midfield halfway through the first stanza as he ran onto a loose ball from just outside the box, only to send the effort well wide.
Shortly thereafter it was Kabelo Dlamini who came close to breaking through as he sent a set-piece narrowly past the target.
Pirates were rewarded in the 36th minute as they opened the scoring to make it 1-0. Terrence Dzvukamanja showcased some silky skills out wide to set up Monnapule Saleng, who finished from right in front.
The hosts had a rare opportunity eight minutes into the second half as Sipho Chaine was forced into a brilliant save to keep the Soweto giants in front.
The result was secured for the Buccaneers just shy of the 70th minute as Ndlondlo scored from the penalty spot after a shove on Bandile Shandu.
The victory leaves Pirates one point below the DStv Premiership's top three, while Gallants' problems deepen at the bottom of the standings.