The East Sussex League was formed as the East Sussex Senior League in 1896 at a meeting held at the Royal Oak in Lewes on 15 May. Previously the strongest teams in the county would play against each other in either cup games or friendlies, the formation of a senior league would allow these teams to regularly compete against teams of a similar standard. The winners of the league would then go onto face the winners of the West Sussex League, also formed that year, in the Irish Rifle’s Cup (now the RUR Cup) to become the overall champions of Sussex.
A junior division was formed ahead of the 1898-99 season, which contained mostly reserves teams of those in the senior division, but this only lasted three seasons. League membership was steady throughout the first decade, however the league saw a decline in numbers after the 1906-07 season and went inactive for three seasons. The number of clubs remained low after reforming, despite the West and Mid Sussex Leagues welcoming additional clubs and divisions and it was not until 1920 the ESFL started to enjoy a consistently healthy number of clubs compete.
By the 1920s all clubs were based in the general Hastings and Eastbourne area, with clubs from west of general catchment area opting to play in the Mid Sussex, Brighton and Lewes leagues. The league saw a gradual increase in membership throughout the 1930s until the outbreak of World War Two in 1939, where it operated an Eastern and Western Section, which saw Hastings Rangers defeat Heathfield United 9-1 in a play-off game played at Wadhurst.
The league reformed in 1946 following the war and membership remained steady, with Rye United, Hollington United and Hastings Rangers dominating the local intermediate football scene around this period. However the formation of Division Two of the Sussex County League would affect the ESFL, whose membership remained steady, but would lose its stronger teams to the County League and the league continued to operate one division at a time leagues of a similar standard in Sussex were constantly increasing. At one point in the 1950s, it was proposed by the chairman of the league to merge with the Hastings League, whose clubs were located not just in the general Hastings and Rother area, but extended to parts of Kent, a larger catchment area than that of the ESFL.
A merger never occurred and the ESFL would go onto increase its membership and form an additional division ahead of the 1959-60 season. The 1960s saw the league expand to five divisions and welcome clubs from Tunbridge Wells, Tenterden and Hawkhurst. League membership remained steady throughout the 1970s and 1980s, and the league formed additional divisions after absorbing the Hastings clubs following the split of the Eastbourne & Hastings League in 1988.
The 1990s saw the likes of Shinewater Association and Seaford win the Premier Division and move onto county football, but membership was on a slow decline. The collapse of the Eastbourne League in 2009 helped boost numbers and an additional division was created. As of 2021 the league is currently formed of six divisions, headed by the Premier Division, the league still has a good number of clubs located along the Sussex/Kent border, which has seen the league also be known as the East Sussex Border League in the past, however some of it’s stronger sides such as Hollington United and Sidley United first teams have moved to the Mid Sussex League in pursuit of a stronger standard of football.