Sidley United were founded in 1906 and were founder members of Division Two of the Sussex County League in 1952.

[7] The 2000–01 season saw Sidley win Division One for the first time in their history, finishing five points ahead of Burgess Hill Town, they also won the John O'Hara League Challenge Cup completing the league and cup double.

[8] The club gained promotion back to Division One at the end of the 2009–10 season, and completed a double by winning the Hastings Senior Cup as well.

The club withdrew from the Sussex County League in 2013 due to the loss of their home ground following the financial collapse of the main social club and went without football that season but resumed playing in the ADA East Sussex Football League for the 2014/15 season in which they finished mid table.

After a couple of top half finishes, the Blues won the ESFL Premier Division in 2018/19.