Pujols, who added an RBI single, went 2-for-6, dropping his major league-leading batting average to .378.
Garrett Stephenson (3-5), who snapped a three-game losing streak, was staked to a big early lead as Cairo's shot gave the Cardinals a 6-0 lead in the third. Cairo also contributed an RBI single in a three-run ninth.
Stephenson became the first St. Louis starter to win in 11 games, allowing two runs and five hits in seven innings.
Jim Edmonds hit a two-run homer in the sixth for the Cardinals that made it 9-1.