Johnson, 27, is in the final year of a four-year deal and is still owed $7 million of his $19.25 million contract for the 2019-20 season.
Johnson has averaged 5.7 points in 16 minutes per game for the Suns this season. Phoenix planned to move on from Johnson after the season and released him with the understanding that there wouldn't be much of a role for him the rest of the season.
Johnson spent parts of his first five NBA seasons in Miami before getting traded to the Suns in 2018. He has averaged 10.5 points, 3.2 rebounds and 2.4 assists in his career, which began as an undrafted player out of Fresno State.
There's expected to be interest in signing Johnson in the marketplace.