The Memphis (Tenn.) Southwind senior is the No. 35 overall prospect in the ESPN 100. A 6-foot-8 lefty, Williams was a reserve forward for USA Basketball's U-17 world championship team this past summer.
During his junior season at Southwind, Williams averaged 15.7 points, 10.2 rebounds and three blocks per game. His team went 28-5 before losing in the state quarterfinals.
Williams gives Missouri a second ESPN 100 commitment, moving the Tigers to No. 16 in the 2013 recruiting class rankings. No. 18-ranked point guard Wes Clark of Romulus, Mich., and No. 42 point guard Travis Jorgenson of Columbia, Mo., already had committed to Missouri.
Williams' brother, Johnny, is a redshirt junior at George Mason.