The deal would reportedly be for 5 years and worth $82 million dollars.
In the video above, taken by Fox 8 producer Nick Kovach, Dan Gilbert confirms Thompson's signing. The announcement was made at a private Cavaliers event held on Wednesday night.
Last season for the Cavaliers, Thompson, 24, played in 82 games, starting 15 of them.
He averaged 8.5 points, 8 rebounds and .5 assists per game.
The Cavaliers regular season begins next Tuesday when they travel to Chicago to take on the Bulls.
Thompson posted on his Instagram account shortly after the news broke.