The 33-year-old former Mamelodi Sundowns, Vitoria Guimaraes and Rangers midfielder was left without a club after parting ways with AmaZulu.
Zungu spent two seasons with Ususthu, featuring 29 times and scoring one goal.
He held talks with a number of potential local suitors but was unable to agree on a deal.
Speaking to SABC Sport, Zungu explained that he was looking for one last contract before calling time on his career.
"I'm 33 years old and close to the finish line in terms of my career," said Zungu.
"I said yes to India because of the offer I got. I was really happy about it, and after the conversation, I felt it was a good move.
“I spoke to a few PSL clubs after leaving Usuthu, but we could not find a solution regarding the offers on the table.”
