The Demons (5-14, 2-7 Southland Conference) have won two straight since snapping a seven-game losing streak. Southeastern Louisiana (3-17, 1-6) has lost 11 of their last 12 games.
Zeek Woodley had 19 points to lead Northwestern State. Sabri Thompson chipped in 17 points and Ta'Jon Welcome added 14.
Jordan Capps scored 19 points and Marlain Veal had 18 for Southeastern Louisiana.
The Lions led 32-30 at halftime. Welcome made a 3-pointer to open the second half, sparking a 29-8 run to give Northwestern State a 59-40 lead with 13 minutes left, and the Demons had a double-digit lead the rest of the way. Welcome scored 10 points, Woodley added seven, and Southeastern Louisiana shot just 3 of 10 from the field during the stretch.