The 1984–85 season was the 70th season of the Isthmian League, which is an English football competition featuring semi-professional and amateur clubs from London, East and South East England.
Sutton United were champions, winning their second Isthmian League title.
Wycombe Wanderers were promoted to the APL, as Sutton United and Worthing were ineligible for promotion.
Epping Town resigned from the league midway through the season and folded.
Division Two North consisted of 21 clubs, including eight clubs transferred from Division Two, one team relegated from Division One and twelve new teams: