Johnson, 27, agreed to a minimum salary deal, according to USA Today's Sam Amick.
A five-year veteran, Johnson spent the last two seasons with the Lakers. Before joining the Lakers, Johnson spent time with the Timberwolves and Suns.
In 76 games for the Lakers in the 2014-15 season, Johnson averaged 9.9 points, 4.2 rebounds and 1.6 assists per game. Over his career, Johnson has averaged 8.5 points, 3.5 rebounds and 1.4 assists per game.
The Timberwolves selected Johnson with the fourth pick of the 2010 NBA draft out of Syracuse.
- Erin Flynn