The 2001–02 season was the 87th season of the Isthmian League, which is an English football competition featuring semi-professional and amateur clubs from London, East and South East England.
The Premier Division consisted of 22 clubs, including 18 clubs from the previous season and four new clubs: Gravesend & Northfleet won the division and were promoted to the Football Conference.
Canvey Island finished second for a second season in a row.
Division One consisted of 22 clubs, including 16 clubs from the previous season and six new clubs: Three clubs relegated from the Premier Division: Three clubs promoted from Division Two: At the end of the previous season Barking ceased to exist when they merged with East Ham United to form Barking & East Ham United, taken place of Barking in Division One.
Ford United won the division and were promoted to the Premier Division along with Bishop's Stortford and Aylesbury United.