The 1997–98 season was the 83rd 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 league consisted of four divisions.
Kingstonian won the division and were promoted to the Football Conference to reach the highest level in the club history. Yeading, Hitchin Town and Oxford City finished bottom of the table and relegated to the First Division.
Before the start of the season Collier Row & Romford F.C. were renamed Romford.
Aldershot Town won the division and were promoted to the Premier Division along with Billericay Town and Hampton. Wokingham Town, Abingdon Town and Thame United relegated to Division Two.
Canvey Island won the division and returned to Division One straight after relegation from it along with Braintree Town and Wealdstone, both achieved the second promotions in two seasons. Tilbury relegated to Division Three along with Egham Town and Abingdon Town.