The Spartan South Midlands Football Leaue was formed in 1922. Originally called the Bedfordshire County League, it changed its name in 1929 to the South Midlands League, following the acceptance of clubs from a much wider area. In 1997 the League expanded when it joined with the London Spartan League, resulting in a much larger League spread over a wider area.

The League is at Step 5 in the Football Association National League Pyramid and covers an area from north London in the south to Milton Keynes in the north, and from Royston in the east to Amersham in the west, and includes clubs from Bedfordshire, Buckinghamshire, Hertfordshire, London and Middlesex.

There are 61 clubs in membership in three divisions, plus a reserve section comprising 39 teams. Clubs in the top two divisions compete in the FA Cup and FA Vase.

Since the FA Vase was introduced in 1974, as the successor to the FA Amateur Cup, the League has had four clubs, Hoddesdon Town, Barton Rovers, Arlesey Town and Hillingdon Borough which have reached the final.