The 1919 World Series matched the American League champion Chicago White Sox against the National League champion Cincinnati Reds. Although most World Series have been of the best-of-seven format, the 1919 World Series was a best-of-nine series (along with 1903, 1920, and 1921). Baseball decided to try the best-of-nine format partly to increase popularity of the sport and partly to generate more revenue.The events of the series are often associated with the Black Sox Scandal, when several members of the Chicago franchise conspired with gamblers, allegedly led by Arnold Rothstein, to throw the World Series games. The 1919 World Series was the last World Series to take place without a Commissioner of Baseball in place. In 1920, the various franchise owners installed Kenesaw Mountain Landis as the first "Commissioner of Baseball."

In August 1921, despite being acquitted from criminal charges, eight players from the White Sox were banned from organized baseball for either fixing the series or having knowledge about the fix.

The Cincinnati Reds are an American professional baseball team based in Cincinnati. The Reds compete in Major League Baseball (MLB) as a member club of the National League (NL) Central division, and were a charter member of the American Association in 1881 before joining the NL in 1890.The Reds played in the NL West division from 1969 to 1993, before joining the Central division in 1994. They have won five World Series championships, nine NL pennants, one AA pennant, and ten division titles. The team plays its home games at Great American Ball Park, which opened in 2003. Bob Castellini has been the CEO of the Reds since 2006. From 1882 to 2021, the Reds' overall win–loss record is 10,713–10,501 (a .505 winning percentage).