The rally was started when Cam Gibson tripled to right field, scoring Brett Pirtle and Jose Azocar. Gibson scored one batter later when Arvicent Perez singled.
Perez later scored in the inning on a single from Derek Hill, before Hill later scored on a Will Maddox single.
The Whitecaps added an insurance run in the seventh inning on an RBI single from Will Allen that scored David Gonzalez.
West Michigan added an insurance run in the eighth inning on a David Gonzalez RBI single that scored Jose Zambrano.
Maddox led the West Michigan offense with four hits while Hill, Gonzalez, Pirtle and Zambrano all had two hits on the night.
Whitecaps starter Sandy Baez picked up his fourth win on the season while striking out six batters in five innings of work.
The Whitecaps will continue their eight game home stand on Tuesday at 7 p.m. against Great Lakes.