1921 St. Louis Cardinals season

The 1921 St. Louis Cardinals season was the team's 40th season in St. Louis, Missouri and the 30th season in the National League. The Cardinals went 87–66 during the season and finished third in the National League.

Regular season
Rogers Hornsby hit .397 in 1921, and his 21 home runs were second in the league. He also led the league in on-base percentage (.458), slugging percentage (.639), runs (131), RBI (126), doubles (44), and triples (18).

Starters by position
''Note: Pos = Position; G = Games played; AB = At bats; H = Hits; Avg. = Batting average; HR = Home runs; RBI = Runs batted in''

Other batters
''Note: G = Games played; AB = At bats; H = Hits; Avg. = Batting average; HR = Home runs; RBI = Runs batted in''

Starting pitchers
Note: G = Games pitched; IP = Innings pitched; W = Wins; L = Losses; ERA = Earned run average; SO = Strikeouts

Other pitchers
Note: G = Games pitched; IP = Innings pitched; W = Wins; L = Losses; ERA = Earned run average; SO = Strikeouts

Relief pitchers
Note: G = Games pitched; W = Wins; L = Losses; SV = Saves; ERA = Earned run average; SO = Strikeouts

Awards and honors

 * Rogers Hornsby, National League batting champion
 * Top 12 Players of the season:
 * Rogers Hornsby (WAR 10.8)
 * Austin McHenry (WAR 5.1)
 * Jack Fournier (WAR 4.2)
 * Bill Doak (WAR 3.0)
 * Verne Clemons (WAR 2.5)
 * Jack Smith (WAR 2.3)
 * Les Mann (WAR 2.3)
 * Milt Stock (WAR 2.0)
 * Doc Lavan (WAR 1.9)
 * Jesse Haines (WAR 1.8)
 * Bill Sherdel (WAR 1.6)
 * Joe Schultz (WAR 1.5)