Middlesex County Cricket Club is one of eighteen first-class county clubs within the domestic cricket structure of England and Wales. It represents the historic county of Middlesex which has effectively been subsumed within the ceremonial county of Greater London. The club was founded in 1864 but teams representing the county have played top-class cricket since the early 18th century and the club has always held first-class status. Middlesex have competed in the County Championship since the official start of the competition in 1890 and have played in every top-level domestic cricket competition in England.

The club plays most of its home games at Lord's Cricket Ground, which is owned by Marylebone Cricket Club, in St John's Wood. The club also plays some games at the Uxbridge Cricket Club Ground (historically Middlesex) and the Old Deer Park in Richmond (historically Surrey). Until October 2014, the club played limited overs cricket as the Middlesex Panthers, having changed from Middlesex Crusaders in 2009 following complaints from Muslims and Jews. On 24 October 2014, the club announced that they would use the name Middlesex County Cricket Club in all forms of the sport with immediate effect. Limited-overs kit colours are dark blue and pink quarters and from 2007, Middlesex have worn exclusive pink shirts during their Twenty20 matches in support of the Breakthrough Breast Cancer charity. The club has an indoor school based in Finchley, the Middlesex Academy and a project at Radlett Cricket Club.

Middlesex have won thirteen County Championship titles (including 2 shared titles), the most recent in 2016. In limited overs cricket, they have won two Benson & Hedges Cups, four one-day cricket titles, one National League and the Twenty20 Cup, through which they became the first county club to qualify for both the Stanford Super Series and the Twenty20 Champions League.

It is almost certain that cricket reached London, and thereby Middlesex, by the 16th century. Early references to the game in London or Middlesex are often interchangeable and sometimes it is not clear if a particular team represents the city or the county.

See: History of cricket to 1696 and History of cricket 1697 - 1725

The first definite mention of cricket in London or Middlesex dates from 1680. It is a clear reference to "the two umpires" (the earliest mention of an umpire in what seems to be a cricket connection) and strongly suggests that the double wicket form of the game was already well known in London.

The earliest known match in Middlesex took place at Lamb's Conduit Fields in Holborn on 3 July 1707 involving teams from London and Croydon. In 1718, the first reference is found to White Conduit Fields in Islington, which later became a very famous London venue.

The earliest known reference to a team called Middlesex is on 5 August 1728 when it played London Cricket Club "in the fields behind the Woolpack, in Islington, near Sadlers Wells, for £50 a side". This was also the earliest known match involving a Middlesex team.