The 2013 St. Louis Cardinals season was the 132nd for the baseball team in St. Louis, Missouri, the 122nd season in the National League (NL), and the eighth at Busch Stadium III. On Opening Day, April 1, the St. Louis Cardinals played the 20,000th game in franchise history against the Arizona Diamondbacks, dating back to the start of their American Association (AA) play in 1882. Heading into the 2013 season, St. Louis had an all-time winning percentage of .518.

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.