Pujols was introduced to baseball early in life by his father, who was a popular pitcher in the Dominican Republic. The Pujols family immigrated to the United States when Albert was 16, and they eventually settled in Independence, Mo. Pujols impressed major league scouts with his play at both the high-school and collegiate level, and he was selected by the St. Louis Cardinals in the 13th round of the 1999 draft. He held out for a better signing bonus, however, and did not enter the minor leagues until the 2000 season. That was his only season in the minors, as an impressive performance in spring training earned him a spot on the Cardinals' 2001 opening-day roster.

Presumed to be a reserve as he entered his first season, Pujols instead played his way into the starting lineup. He appeared in 161 games, posted a .329 batting average with 37 home runs and 130 runs batted in (RBIs), and was the unanimous choice for 2001 National League (NL) Rookie of the Year. Pujols continued to put up impressive offensive numbers in the following seasons and was twice (2002 and 2003) the NL Most Valuable Player (MVP) runner-up to Barry Bonds (Bonds, Barry). Pujols collected a number of other awards, including the 2004 NL Championship Series MVP and Silver Slugger awards in 2001, 2003, and 2004. In 2005 he hit .330 with 41 home runs and 117 RBIs and was named NL MVP.

In 2006 Pujols bettered the batting statistics of his previous season, hitting .331 with 49 home runs and 137 RBIs, and finished as MVP runner-up for the third time in his short career. That year he also experienced his greatest postseason success, as he helped lead St. Louis to a commanding four-games-to-one win over the heavily favoured Detroit Tigers in the World Series, giving the Cardinals their first title since 1982. In 2008 Pujols was named NL MVP after finishing the season with a .357 batting average and 116 RBIs.