The controversial New Zealand-born play-maker is currently serving a ban after testing positive for cocaine when playing for Widnes Vikings two years ago.
He will begin training with the club today (Tuesday, May 14) and is eligible to play from July 14.
Chase began his Super League career with Castleford Tigers in 2009 and was named Man of Steel, the game’s highest individual accolade, two years later.
He had spells with Salford Red Devils and Leigh Centurions and returned to Castleford for a seven-game stint in 2016-17 before moving to Widnes.
Chase, who qualified for England on residency grounds and was capped eight times, said: “It feels good to be back, I’m really looking forward to getting involved and helping the lads at the business end of the season.
“I’m excited as I’ve had a long time out.
“Now that it’s not too far away I’m working hard to get my fitness levels as high as possible.
“The training will help me to get back up to speed. I want to try and get ready for July and get to know the boys as well.”
Doncaster chief executive Carl Hall said: “We’re delighted to be able to bring a player of Rangi’s quality to the club.
“He is someone I have known for a number of years and I have always stayed in contact with him.
“We’re giving him an opportunity to show what he’s capable of in a Dons shirt and, without putting any pressure on him, I believe he’s the biggest signing this club has made since Tony Kemp.
“I hope everyone is excited as I am to see him play.”