In the early years after formation, the club participated in mainly friendly games against other British university baseball teams, as no formal university league was in existence. Starting in 1998, the Mustangs started to host a university Baseball tournament - inviting other teams including Oxford, Cambridge, Portsmouth, Royal Holloway, and Norwich.
In 2004 the Mustangs took the decision to enter into the national adult baseball leagues run by the British Baseball Federation (BBF). By this time, the club had grown in size and experience - meaning that there were sufficient players available to play weekly, including over University holiday dates. As a new team to the league, the club entered in the lowest division (division 2 south at that time). After a few years of consolidation, the Mustangs have worked their way up from the lower leagues in the BBF to now play in the National Baseball League (NBL) going into the 2010 season. The British National Baseball League is the top-tier league of the British Baseball League, with the aim of establishing flagship British Baseball clubs.
Since their first season in 2004, the club has been climbing the British baseball leagues. In 2006 they won promotion with a regular season record of 10-2 in the AA League. The following year they reached the AAA postseason at the first time of asking, losing to the Essex Arrows in the Semi-Final of the National Baseball Championship. In 2009 they once again reached the postseason and just missed out on the AAA League Championship losing to the Harrogate Tigers in the Final.
The Mustangs II compete in the A division and is developmental side for those new to the sport, or with less experience.
The Mustangs play at Southampton University's Wide Lane sports Ground, at Mustang Field.