The 30-year-old's decision was revealed by coach Gordon Igesund in a press conference this afternoon.
"I am disappointed that Steven has retired from the national team," said Igesund. "But the way he has retired is the right way. I think it was a tough decision for him."
Johannesburg-born Pienaar made 57 appearances for his country, scoring two goals.
The attacker has withdrawn his services just three months before his nation hosts the Africa Cup of Nations.