Mickey spent parts of the last two seasons with the Boston Celtics, appearing in 41 regular-season games and four postseason games. He averaged 1.5 points, with career highs of eight points, five rebounds and 19 minutes.
Mickey averaged 20.8 points and 8.8 rebounds for the Maine Red Claws of the NBA G League last season. He was the 33rd overall pick in the 2015 NBA Draft out of LSU, where he blocked 100 shots in back-to-back seasons.
The Heat signed him Sunday.