Jefferson's deal was agreed upon last month and reported by The Associated Press and several media outlets. The 14-year veteran will give the Cavs another experienced wing player who can spread the floor as well as back up LeBron James.
Jefferson spent last season with Dallas and had been expected to re-sign with the Mavericks. However, the chance to chase an NBA title lured him to the Cavs, who made it to the finals this season before losing in six games to Golden State.
The 6-foot-7 Jefferson has averaged 13.9 points in his career and appeared in 105 playoff games. Last season, he averaged 5.8 points and 16.8 minutes in Dallas.
Jefferson made it to the finals twice with New Jersey.