Miller -- a 13-year NBA veteran who had two years left on his five-year, $25 million contract with Miami -- averaged career lows of 4.8 points, 2.7 rebounds and 15.3 minutes per game during the 2012-13 season. He appeared in 17 of the Heat's 23 post-season games, averaging 3.4 points.
In three seasons with the Heat, Miller, averaged 5.4 points, 3.4 rebounds and 1.4 assists per game.
He was due to earn $6.2 million in the 2013-14 season.
"After many discussions internally and a sincere effort to explore the trade market, we made a very difficult decision to use our Amnesty provision on Mike Miller," Heat President Pat Riley said in a statement. "Mike had an incredible impact on the Miami Heat; helping us to three finals appearances and winning back-to-back world championships."
Rile called the decision "very difficult" for the Heat organization.
Miller was selected No. 5 overall in the 2000 NBA Draft by the Orlando Magic and was named Rookie of the Year in 2000-01 and Sixth Man of the Year when he played with the Memphis Grizzlies in 2005-06.
He averaged 12.3 points, 4.8 rebounds and 2.9 assists per game in his NBA career.