|Duration||September 20 – December 20, 1925|
|A controversial ruling by the NFL suspended the Pottsville Maroons from all league privileges, including the right to play for the NFL championship.|
The 1925 NFL season was the sixth regular season of the National Football League. Five new teams entered the league: New York Giants, Detroit Panthers, Pottsville Maroons, Providence Steam Roller, and a new Canton Bulldogs team. The Kenosha Maroons folded, with the Racine Legion and Minneapolis Marines mothballing.
Controversy surrounds who actually won the 1925 NFL Championship. Officially, the Chicago Cardinals are listed as the 1925 NFL champions because they finished with the best record; however, many Pottsville fans at the time claimed that the Maroons were the legitimate champions. The Maroons and the Cardinals were the top contenders for the title, with Pottsville winning a late-season meeting between them, 21–7. But the Maroons scheduled a game against a team of University of Notre Dame All-Stars in Philadelphia (and winning 9–7) on the same day that the Frankford Yellow Jackets were scheduled to play a game in the same city. Frankford protested, saying that it was violating their protected territory rights.
Although NFL president Joe Carr warned the Maroons in writing that they faced suspension if they played in Philadelphia, the Maroons claimed that Carr approved the game during a telephone call, and played anyway. In response, Carr fined the club, suspended it from all league rights and privileges (including the right to play for the NFL championship), and returned its franchise to the league.
In 2003, the NFL decided to again examine the case regarding the 1925 championship. In October of that year, the NFL voted 30–2 not to reopen the case, with only Philadelphia and Pittsburgh, the league's two Pennsylvania-based teams, voting in favor. Thus, the Cardinals are still listed as the 1925 NFL champions. 
Had the current (post-1972) system of counting ties as half a win and half a loss been in place in 1925, the Maroons would have won the championship with a win percentage of .833, while the Cardinals would have finished runner-up at .821.
|Chicago Cardinals *||11||2||1||.846||229||65||W2|
|Pottsville Maroons *||10||2||0||.833||270||45||W5|
|New York Giants||8||4||0||.667||122||67||W1|
|Frankford Yellow Jackets||13||7||0||.650||190||169||W2|
|Rock Island Independents||5||3||3||.625||99||58||L1|
|Green Bay Packers||8||5||0||.615||151||110||W1|
|Providence Steam Roller||6||5||1||.545||111||101||L1|
|Kansas City Cowboys||2||5||1||.286||65||97||W1|
Note: Tie games were not officially counted in the standings until 1972.
* The Pottsville Maroons were suspended from the league in December, resulting in the Chicago Cardinals being named the NFL champions.
- Herb Stein, Pottsville Maroons
- Joey Sternaman, Chicago Bears
- Jack McBride, New York Giants
- Akron Pros: Scotty Bierce
- Buffalo Bisons: Walt Koppisch
- Canton Bulldogs: Harry Robb
- Chicago Bears: George Halas
- Chicago Cardinals: Norman Barry
- Cleveland Bulldogs: Cap Edwards
- Columbus Tigers: Red Weaver
- Dayton Triangles: Carl Storck
- Detroit Panthers: Jimmy Conzelman
- Duluth Kelleys: Dewey Scanlon
- Frankford Yellow Jackets: Guy Chamberlin
- Green Bay Packers: Curly Lambeau
- Hammond Pros: Fritz Pollard (1 game) and Doc Young (4 games)
- Kansas City Cowboys: Roy Andrews
- Milwaukee Badgers: Johnny Bryan
- New York Giants: Bob Folwell
- Pottsville Maroons: Dick Rauch
- Providence Steam Roller: Archie Golembeski
- Rochester Jeffersons: Tex Grigg
- Rock Island Independents: Rube Ursella
- "Pottsville Maroons: NFL owners refuse to reconsider 1925 ruling". Archived from the original on October 21, 2009.
- Chris Willis (2010-08-19). The Man Who Built the National Football League: Joe F. Carr. p. 217. ISBN 9780810876705.