Chalmers used Instagram to post a picture of himself in a Grizzlies uniform with a caption that read "GNG... enough said." Grit and grind is the Grizzlies' motto.
Multiple media outlets reported that Chalmers agreed to a one-year deal.
Chalmers, 31, has recovered from a torn right Achilles tendon he suffered in March 2016 while playing for the Grizzlies.
The Grizzlies released Chalmers after he was injured, and he missed the entire 2016-17 NBA season.
The Grizzlies acquired Chalmers from the Heat in a trade that sent Beno Udrih to Miami early in the 2015-16 season.
Chalmers averaged 10.8 points, 3.8 assists and 1.5 steals in 55 games with the Grizzlies in 2015-16.
Chalmers is likely to be a backup at both guard positions.