He inked a multi-year contract. Terms were not disclosed.
Williams, the 45th overall pick in the draft in June, was named Mr. Basketball in Georgia as a junior and senior while at South Gwinnett High School in suburban Atlanta. He had 3,338 points, 768 rebounds, 650 assists and 355 steals during his high school career and last year earned the Naismith Award as the top high school player in the nation.
"I think in my first year my role will be to provide energy on the practice court and push guys while improving my game," Williams said on the 76ers' Web site. "I will work real hard to get better and help my team to get better."