Williams was a first-round pick by Boston in 2018, getting selected 27th overall out of Texas A&M. Some knee tendinitis caused the Celtics to ease Williams into their rotation, and back soreness as well as some time in the G League ultimately limited him to 32 NBA games in his rookie year. Though his opportunities were limited, Williams showed the ability to take advantage and impact the game as a rebounder and shot blocker. On Dec. 10, he collected 11 rebounds and three blocks against the Pelicans. The month of December also saw Williams record a pair of five-block efforts. He collected a season-high eight points in one of those games, shooting 4-for-4 and adding eight boards in a Dec. 19 effort against Phoenix. Such effective shot selection was typical for him, as Williams delivered an incredible 70.6 field-goal percentage on the season, though his limited opportunities held him to 2.5 points and 2.5 rebounds per game -- along with an impressive 1.3 blocks. Though he was lightly used during the Celtics' nine-game playoff run, Williams contributed when given the opportunity. He played nearly nine minutes in Game 2 of Boston's second-round series against the Bucks, delivering four points and five rebounds.
June 21, 2018Drafted by the Boston Celtics in the 1st round (27th pick) of the 2018 NBA Draft.
July 5, 2018Signed a two-year contract with the Boston Celtics. Agreement includes a third year club option.