The St. Louis Cardinals' 2011 season was the team's 130th season in St. Louis, Missouri, its 120th season in the National League, and its sixth season at Busch Stadium III. The Cardinals began their season at home against the San Diego Padres on March 31, following an 86–76 (.531) record and second-place finish in the National League Central in 2010. The team returned to postseason play in 2011 as the Wild Card team, after finishing second in the NL Central to the Milwaukee Brewers by six games. The Cardinals beat the Philadelphia Phillies in five games in the NLDS and the Milwaukee Brewers in six games in the NLCS. They defeated the Texas Rangers in the World Series in seven games.

The St. Louis Cardinals are an American professional baseball team based in St. Louis. The Cardinals compete in Major League Baseball (MLB) as a member club of the National League (NL) Central Division. Since the 2006 season, the Cardinals have played their home games at Busch Stadium in downtown St. Louis. One of the nation's oldest and most successful professional baseball clubs, the Cardinals have won 11 World Series championships, the most of any NL team and second in MLB only to the New York Yankees. The team has won 19 National League pennants, third-most of any team behind the Los Angeles Dodgers and San Francisco Giants. St. Louis has also won 15 division titles in the East and Central divisions.