2019–20 Isthmian League

The 2019–20 season was the 105th season of the Isthmian League, which is an English football competition featuring semi-professional and amateur clubs from London, East and South East England. This was the second season to consist of four divisions after the league reorganised the former South Division into the new South Central and South East divisions.

As a result of the COVID-19 pandemic, this season's competition was formally abandoned on 26 March 2020, with all results from the season being expunged, and no promotion or relegation taking place to, from, or within the competition. On 30 March 2020, sixty-six non-league clubs sent an open letter to the Football Association requesting that they reconsider their decision. A legal appeal against the decision, funded by South Shields of the Northern Premier League, was dismissed in June 2020.

Premier Division
The Premier Division consisted of 22 clubs, including 17 clubs from the previous season, and five new clubs:
 * Bowers & Pitsea, promoted from the North Division
 * Cheshunt, promoted from the South Central Division
 * Cray Wanderers, promoted from the South East Division
 * East Thurrock United, relegated from the National League South
 * Horsham, promoted from the South East Division

North Division
North Division consisted of 20 clubs, 17 clubs from the previous season, and three new clubs:
 * Cambridge City, transferred from the Southern Football League Division One Central
 * Histon, promoted from the Eastern Counties League
 * Hullbridge Sports, promoted from the Essex Senior League

South Central Division
South Central Division consisted of 20 clubs, 16 clubs from the previous season, and four new clubs:
 * Barking, transferred from the North Division
 * Chertsey Town, promoted from the Combined Counties League
 * Harlow Town, relegated from the Premier Division
 * Staines Town, relegated from the Southern Football League Premier Division South

South East Division
South East Division consisted of 20 clubs, 16 clubs from the previous season, and four new clubs:
 * Burgess Hill Town, relegated from the Premier Division
 * Chichester City, promoted from the Southern Combination League
 * Cray Valley Paper Mills, promoted from the Southern Counties East League
 * Whitehawk, relegated from the Premier Division

League Cup
The 2019–20 Alan Turvey Trophy (formerly the Isthmian League Cup) is the 46th season of the Alan Turvey Trophy, the cup competition of the whole Isthmian League. It was the first season when group stage was introduced.

Group stage
57 clubs from the North Division, South East Division and South Central Division entered at this stage, while Guernsey, Whitehawk and Dereham Town decided not to participate.

First round
Ten group winners were entered into the draw with twenty-two clubs from the Premier Division, making thirty-two clubs.

Semi-finals
Semifinals were scheduled for 17 March, but were never played as the season was stopped and finally abandoned on 26 March due to COVID-19 pandemic.