Speaking at a news conference in Miami, Riley and Heat Managing General Partner Micky Arison said Miami Assistant Coach/Director of Scouting Erik Spoelstra, 37, would be made the sixth head coach in franchise history.
"This game is now about younger coaches who are technologically skilled, innovative and bring fresh new ideas," Riley said. "That's what we feel we are getting with Erik Spoelstra. He's a man that was born to coach."
The Heat were 15-67 in the season that just ended -- the worst season in the 25-year coaching career of Riley, who was elected into the Basketball Hall of Fame earlier in April.
The dreadful result comes just two seasons after Riley led the Heat to the NBA championship, the fifth title of his coaching career. However, Miami is 59-105 since winning the 2006 championship.
Riley has piled up 1,210 victories, which is third on the NBA all-time list.