The 1920 Akron Pros were named the first APFA (NFL) champions.
The National Football League champions, prior to the merger between the National Football League (NFL) and American Football League (AFL) in 1970, were determined by two different systems. The National Football League was established on September 17, 1920 as the American Professional Football Association (APFA). The APFA changed its name in 1922 to the National Football League, which it has retained ever since. From 1920 to 1931, the APFA/NFL determined its champion by overall win–loss record, with no playoff games; ties were not counted in the winning percentage total. Although the APFA did not keep records of the 1920 season, they declared the Akron Pros, who finished the season with an 8–0–3 (8 wins, 0 losses, 3 ties) record, as the league's first champions. The Canton Bulldogs won two straight championships from 1922 to 1923, and the Green Bay Packers won three in a row from 1929 to 1931.
^No official standings were recorded for the 1920 season and teams played games against opponents outside of the league. The championship was awarded to the Akron Pros in an APFA meeting on April 30, 1921.
^Chicago and Portsmouth finished with identical win–loss records, tying for first place in the NFL. To solve the tie, a playoff game was held between the two, counting towards the regular-season total. Chicago won the game and the championship while Portsmouth's loss dropped them to third place, behind Green Bay.
1 – From 1966 to 1969, the first four Super Bowls were "World Championship" games played between two independent professional football leagues, AFL and NFL, and when the league merged in 1970 the Super Bowl became the NFL Championship Game. 2 – Dates in the list denote the season, not the calendar year in which the championship game was played. For instance, Super Bowl XLI was played in 2007, but was the championship for the 2006 season.