The 6-foot-9 forward averaged 11.9 points, 8.2 rebounds and 2.5 blocks this past season and came out of nowhere to explode onto NBA executives' draft boards.
One NBA general manager told ESPN that Williams would have likely been selected in the 10-to-20 range this June.
"I love A&M and it was a great experience which helped me grow and get better as a player and a person," Williams said in a statement. "Although I've grown, I still feel like I would benefit from another year of college. This will give me more time to mature and develop my game before moving on to the NBA."
"I know this was a difficult decision for him and his family," Aggies coach Billy Kennedy said. "He's not only a special talent but a special young man. His desire to be the best and his trust in us [is] humbling."