The 2011 National League Championship Series was a best-of-seven playoff pitting the winners of the 2011 National League Division Series, the St. Louis Cardinals and Milwaukee Brewers, against each other for the National League championship and the right to be the league's representative in the 2011 World Series. The series was the 42nd NLCS in league history.

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.