The 1975–76 season was the 61st in the history of the Isthmian League, an English football competition.
It was the last Isthmian League season to use goal average as a tie-breaker.
Enfield won Division One, while Tilbury won Division Two.
Division One featured 22 clubs, including 20 clubs from the previous season and two clubs, promoted from Division Two:
Division Two expanded up to 22 clubs, including 16 clubs from the previous season and six new clubs: