Terms of the deal were not disclosed, but the Oakland Tribune said it was for one year and $7 million.
The 10-year veteran spent last year with Charlotte and averaged 7.9 points and 6.8 rebounds in 66 games.
The No. 1 overall pick of Washington in 2001, he has played in 576 games in the NBA with Washington, the Los Angeles Lakers, Memphis, Detroit and Charlotte.
During that time, he has averaged 22.5 minutes, 6.8 points and 5.6 rebounds per game.