Jamal Ferguson, of Norfolk (Va.) Maury, gave Williams a verbal pledge Thursday afternoon. He confirmed the new to Scout.com.
"I picked Marquette because I believe I can become a better player, and I believe that coach Buzz can turn me into a great player," Ferguson said.
"I really like environment and people down there," he added. "Also, coach [Aki] Collins played a big part in my decision."
Ferguson, a 6-foot-4, 180-pound wing prospect, is currently rated as a three-star prospect. He's averaging 17 points and just over seven rebounds a game mid-way through his junior season.