1899–1900 Northern Rugby Football Union season
||Separate county championships
|| Sam Williams 108
|| Sam Williams 36
|Lancashire Senior Competition
|Yorkshire Senior Competition
The 1899–1900 Northern Rugby Football Union season was the fifth season of rugby league football.
The Lancashire Senior Competition was won by Runcorn (from Cheshire) and the Yorkshire Senior Competition by Bradford.
Hull Kingston Rovers played their first season in the Northern Rugby Union this season. Their first match away at Bradford on 2 September ended in a 3-0 defeat.
Lancashire Senior Competition
Millom replaced Morecambe. Although participating in the Lancashire Senior Competition, Runcorn and Stockport were from Cheshire, and Millom were from Cumberland.
- Two league points deducted for breach of professional rules.
Yorkshire Senior Competition
Swinton beat Salford 16-8 in the Challenge Cup final at Fallowfield Stadium, Manchester played before a crowd of 17,864.