The two-year deal is worth $10 million, sources told ESPN.com.
Booker's agent confirmed the signing via Twitter.
- ASM SPORTS (@ASM_SPORTS) July 15, 2014
Booker averaged 6.8 points and 5.3 rebounds in 72 games (45 starts) for the Wizards last season.
The Wizards had the option of making Booker a restricted free agent last month but decided not to offer him a qualifying offer, and they lost their matching rights.
Yahoo! Sports first reported the deal.