Justin Shonga scored an 84th minute winner for the Buccaneers after Leonardo Castro cancelled out Thembinkosi Lorch's early opener for the Absa Premiership leaders at Durban's Moses Mabhida Stadium on Saturday.
Lorch drew first blood in the 13th minute as he turned in a low cross by Vincent Pule after Mario Booysen missed a long clearance by Jackson Mabokgwane.
However, Colombian hitman Castro equalised barely five minutes later as he exploited indecision by Mabokgwane and Happy Jele to touch home a ball hoisted into the box to leave things level at the break.
In the second half, Xola Mlambo was denied by the top of the crossbar after unleashing a shot from outside the box following a loose ball from a corner kick.
Twisting and turning from Pule on the right side ended with him taking a cross-cum-shot which flew across the face of Itumeleng Khune’s goal.
Chiefs looked to the bench for inspiration and introduced the veteran Bernard Parker in the 68th minute for Lebogang Manyama to liven up their offensive options.
Bucs then brought on their first substitution as well in the form of Augustine Mulenga for Thabiso Kutumela.
Searching for the winner led to end-to-end attacks on the counter on either side, but the finishing in the final third was largely lacking.
Bucs, though, seized the initiative six minutes from time when Shonga dusted himself off from a failed bicycle kick to beat Khune with a bottom-corner finish.
Chiefs instantly threatened an equaliser, but Booysen was unable to get his header from a cross from the right on target.
Shonga searched for his brace in added time, as his curler missed the top corner by inches.
At the death, Mabokgwane pulled off a save to deny Booysen to guide them in the final.
Chiefs: Chiefs: Khune, Mphahlele, Booysen, Ngezana, Walusimbi, Katsande, Maluleka, Billiat, Manyama (Parker 68’), Zuma (Mahlasela 87’), Castro.
Subs: Vries, Cardoso, Mahlasela, Ntiya-Ntiya, Zulu, Andrianarimanana, Parker
Pirates: Mabokgwane, Munetsi, Jele, Maela, Mbekile, Nyatama, Mlambo, Pule (Makola 90+1’), Kutumela (Mulenga 68’), Lorch (Da Silva 90+4’), Shonga.
Subs: Mpontshane, Da Silva, Mobara, Makola, Mntambo, Qalinge, Mulenga.