Just a day after terminating his contract with Rangers, Forrester has signed on with Tractor Sazi, an Iranian side managed by John Toshack.
Forrester moved to Rangers from Doncaster Rovers in January 2016, and scored eight goals in 44 appearances.
He spent last season on loan with AFC Wimbledon.
The midfielder will now try his luck with Tractor Suzi, who finished 10th in the 16-team Persian Gulf Pro League.
He told supporters on Tractor Suzi's Instagram account: "Hello Tractor fans, Harry Forrester [here]. I am looking forward to a successful season and I will see you all soon."