It was UNCW's first win in Harrisonburg since 2006.
The Seahawks hit 9 of 15 3-pointers (60 percent), led by Jackson's four makes and Ponder's three.
UNCW scored 18 of its 37 first-half points off of 10 JMU turnovers and led by 14 points after closing the half on a 14-3 run.
Ron Curry scored 21 points for James Madison (13-11, 6-5), his fourth 20-plus point game this season. He was 5 of 12 from the field and 9 of 11 from the free throw line. Tom Vodanovich had 12 points and Joey McLean 11.