Reynaldo Rivera helped West Michigan take an early lead when he singled home Luke Burch and Garrett McCain, giving West Michigan a 2-0 lead. That lead extended to 3-0 one batter later when Colby Bortles singled home Jordan Pearce.
The score remained 3-0 in favor of West Michigan until the fourth inning when Peoria scored twice.
In the sixth inning, Juan Yepez of Peoria scored on an error to tie the game at 3-3.
In the tenth inning, West Michigan took a 4-3 lead on a Rivera double that scored Pearce.
However, Peoria scored twice in the home half of the inning to earn the walk-off win. Yariel Gonzalez had the game winning RBI, singling home Nick Plummer.
Overall, West Michigan was led on offense by Rivera who finished with two hits and three RBIs while Cole Peterson also had two hits.
Whitecaps starter Garrett King tossed six innings, allowing two earned runs on seven hits while striking out eight.
West Michigan is now 14-10 on the season and 1 and ½ games behind Lansing for first place in the Midwest League Eastern Division.
The Whitecaps will continue their series at Peoria on Wednesday with first pitch at noon.