The Colonels (7-3) trailed 37-33 at halftime but took the lead for good at 45-44 on Williams' 3-pointer with 14:14 left. That basket began a 22-5 run that left the Colonels up 64-49 at 7:53.
The Lancers (3-7) got back within eight points with 4:12 left but another Williams' 3-pointer plus four EKU free throws built the lead back to 15 with a minute left.
Williams, who played 24 minutes off the bench, made all four of his 3-pointers in the second half.
Longwood shot 57.9 percent, including 9 of 16 3-pointers, and had a rebounding edge. However, they were hurt by 22 turnovers that turned into 33 EKU points.