The 1908–09 Northern Rugby Football Union season was the 14th season of rugby league football in the United Kingdom. The governing body, the Northern Union (NU) decided to admit four extra clubs, all from Wales; Aberdare, Barry, Mid-Rhondda and Treherbert , to expand the Northern Rugby League to 31 clubs. With six Welsh clubs in the league the NU also established a Welsh League along the same lines as the existing Lancashire and Yorkshire leagues. Wigan won the Lancashire League. Halifax won the Yorkshire League. The Welsh League was won by Ebbw Vale.