1990–91 Northern Football League

The 1990–91 Northern Football League season was the 93rd in the history of Northern Football League, a football competition in England.

Division One
Division One featured 17 clubs which competed in the division last season, along with three new clubs, promoted from Division Two:
 * Murton
 * Northallerton Town
 * Peterlee Newtown

Division Two
Division Two featured 17 clubs which competed in the division last season, along with two new clubs, relegated from Division One:
 * Billingham Town
 * Easington Colliery