Thomas signed a contract with the Celtics on Friday, Keith Smith of Spotrac.com reports.
Thomas appeared in 12 games for the Celtics last season, playing 60 total minutes. He spent much more time in the G League, averaging 14.6 points, 5.6 rebounds, 3.9 assists and 1.6 steals in 30.8 minutes. The guard will try to impress enough during camp to make a final roster spot.