St. Louis finished as the No. 5 seed in the National League and will face the San Diego Padres in the wild-card series.
The accomplishment is noteworthy considering the Cardinals' season was temporarily derailed after a COVID-19 outbreak struck the team in late July, which forced the club to play 11 doubleheaders between mid-August and the end of September.
Milwaukee claimed the No. 8 seed and will play the Los Angeles Dodgers in the wild-card round.
"There's no reason to apologize for getting into the playoffs. ... We've got a chance to win the World Series," Brewers manager Craig Counsell said postgame Sunday, according to Adam McCalvy of MLB.com.
The Giants and Phillies were eliminated from contention with their losses.