Jabulani Shongwe had given the Students a 26th minute lead in a tempered affair, before second half Erasmus and Sifiso Myeni goals sealed the title for the Buccaneers.
They had come into the game with a cloud hanging over them after they lost three previous finals this season, but made no mistake the fourth time of asking to win a match that drew the curtain on the domestic calendar.
Pirates came flying out of the blocks and should have taken the lead inside the opening minute when the ball was threaded through to Erasmus from midfield, but the striker, who did excellently to turn inside a defender, saw his low shot expertly blocked by Moeneeb Josephs.
The Buccaneers continued to press forward and had a strong penalty appeal turned down in the eighth minute when a Daine Klate free-kick caused some panic in the box and the ball appeared to strike the hand of Sboniso Gumede, although referee Zolile Mthetho felt otherwise.
The goal arrived before the half-hour mark when Sthembiso Ngcobo played a short pass to Shongwe on the left and the former Mamelodi Sundowns midfielder took a touch forward, before rifling past Senzo Meyiwa.
The Students could have had a penalty in the build-up anyway as Calvin Kadi was sliced down inside the box by Happy Jele.
Wits continued to press forward and Kwanda Mngonyama headed wide not long after, while Thabo Matlaba had a shot from outside the box fly over as Gavin Hunt’s men lead at the break.
After the restart, Ngcobo stung the palms of Meyiwa after a quickly taken free-kick, before Pirates drew level when Oupa Manyisa escaped down the right and cut the ball back expertly to Erasmus, who thumped in via a deflection of Mngonyama after 52 minutes.
The response was excellent from Wits as replacement Asive Langwe headed a Sibusiso Vilakazi ball wide at the near post, before Ngcobo forced Meyiwa to tip over after a clever header from a throw-in flew towards the top right-hand corner.
However, Pirates then hit them on the break to surge ahead in the 62nd minute as Manyisa managed to squeeze in a low cross from the right that was converted by Myeni.
Straight after the game threatened to boil over as a flying Phumlani Ntshangase tackle on Klate drew a reaction from the winger and prompted both benches to get involved.
The Wits player ended up with a yellow card for his late lunge.
That seemed to unsettle the Hunt’s team and they fell 3-1 behind in the 71st minute when Erasmus squared the ball to the centre of the box and continued his run, and after Manyisa scuffed his shot, the Bafana Bafana forward was on hand to thump in.
Ryan Chapman and Vilakazi had late chances to pull a goal back, but failed to take them with Pirates holding on to clinch the title for the eighth time in their history.