Junior Miranda Rudacille scored with 13 seconds remaining in regulation for the Hornets (12-3, 8-1 ODAC) and then SU scored three of the game's four overtime goals to secure the win.
Women's lacrosse plays an eight-minute overtime.
Senior Liz Bereit, who had six goals on the day, tallied the game-winner with 1:05 remaining in overtime.
VWC (9-8, 4-6) had scored the initial goal of OT before Rudacille and Cortney Gensemer scored in the final minute of the first half of the extra session.
The Marlins got an unassisted goal 73 seconds into the second half OT, knotting the game at 16-16.
Bereit led the victors with six goals and two assists for eight points while Rudacille had fourgoals and three assists.
Virginia Wesleyan outshot the Hornets 41-34 and had slight, 32-30 and 19-17, advantages in groundballs and draw controls, respectively.
Hornets goalkeeper Rachel Levy had 16 saves in the win.
Shenandoah has one game remaining in the regular season: at Randolph-Macon Wednesday afternoon. The winner of that game claims second place in the league standings and the accompanying bye into the ODAC Tournament semi-finals.