The experienced full-back was released by the Buccaneers last month having made only nine appearances in all competitions in one-and-a-half seasons at the Houghton-based club.
Van Heerden had joined Pirates midway through the 2016/17 campaign from Chippa United, but he struggled for game time with Thabo Matlaba and Innocent Maela preferred ahead of him.
Van Heerden is now eager to prove his quality at Usuthu, who managed to retain their status in the elite league.
"I do not hold grudges but I was stressed at Pirates. That's why I decided to come back to AmaZulu. I want to prove that I can still offer a lot in football," Van Heerden told SowetanLive.
Lack of game time was the main reason the Johannesburg-born player has returned to Usuthu for his second spell with the club.
"As much as I was frustrated because of limited game time, it was a huge learning curve for me. It is such times that make you to be a better and stronger person," he said.
"I don't know why I did not play but I remained professional by doing all I had to do," he continued.
Van Heerden attracted interest from two other PSL clubs, but he decided to return to the Durban-based side.
"There were two teams that were interested but I decided to join AmaZulu because of their ambitions. The club have huge ambitions. I want to be part of that," he revealed.
"This club is very close to my heart. It's a space that I am familiar with. The move is also good for my family," he continued.
"We obviously want to win stuff. We will do our best to challenge for trophies," Van Heerden concluded.