The 2018–19 season was the 104th season of the Isthmian League, which is an English football competition featuring semi-professional and amateur clubs from London, East and South East England.
At the end of the previous season a new step 3 division was created under the Southern Football League, while the number of clubs in the Premier divisions was reduced to 22 for this season.
The number of clubs in the step 4 divisions was reduced to 20 for the next season.
The number of clubs in the step 4 divisions was reduced to 20 for the next season.
The 2018–19 Alan Turvey Trophy (formerly the Isthmian League Cup) was the 45th season of the Alan Turvey Trophy, the cup competition of the whole Isthmian League.