After a scoreless first half, Amy Sibik tallied her tenth goal of the year as she scored at 56:03 on a pass from Amanda Rahman.
The Cardinals' second goal came at 72:40 as Kelsey Peyton scored her first of the season from Tania Trowbridge.
Saint Mary's out-shot the Pipers 13-6 in the game but had just one corner kick to the Pipers' seven.
Hamline is now 4-10-0, 0-8-0 MIAC while the Cardinals are 7-6-1, 4-3-1 MIAC. The Pipers play a non-conference contest on Tuesday, October 19, hosting Northwestern College at 3:30 p.m.