The fifth-ranked Blue Devils announced Williamson's status Thursday morning after he had missed nearly six full games with a knee sprain.
The 6-foot-7, 285-pound Williamson was hurt in the opening minute of last month's loss to North Carolina. The Blue Devils had been 3-3 with Williamson out.
Williamson - The Associated Press' player and newcomer of the year in the ACC - is averaging 21.6 points and 8.8 rebounds.
Coach Mike Krzyzewski had been publicly optimistic Williamson would return for the ACC Tournament. He said Williamson performed well in non-contact practice work last week and his status would depend on how he responded to contact work this week.
MORE: No. 6 seed Syracuse (20-12, 11-8) vs. No. 3 seed Duke (26-5, 14-4)
BOTTOM LINE: Syracuse and Duke are prepared to match up in the quarterfinals of the ACC tournament. The teams split the regular season series at one win apiece. The teams last faced each other on Feb. 23, when the Blue Devils shot 44.1 percent from the field while holding Syracuse to just 34.3 percent en route to a 10-point victory.
FRESHMAN QUARTET: Duke has relied heavily on its freshmen this year. R.J. Barrett, Zion Williamson, Cam Reddish and Tre Jones have combined to account for 75 percent of the team's scoring this year and 65 percent of all Blue Devils points over the last five games.
FACILITATING THE OFFENSE: Barrett has directly created 57 percent of all Duke field goals over the last five games. The freshman forward has 51 field goals and 27 assists in those games.
SCORING THRESHOLDS: Syracuse is 16-0 when it limits opponents to 63 or fewer points, and 4-12 when opposing teams exceed 63 points. Duke is 23-0 when holding opponents to 72 points or fewer, and 3-5 whenever teams score more than 72 on the Blue Devils.
PERFECT WHEN: The Blue Devils are 23-0 when they hold opposing teams to 72 points or fewer and 3-5 when opponents exceed 72 points. The Orange are 16-0 when they hold opponents to 63 points or fewer and 4-12 when opponents exceed 63 points.
DID YOU KNOW: Duke is ranked seventh nationally by scoring 84.1 points per game this year. Syracuse has only averaged 69.7 points per game, which ranks 229th.