London 3 South West is an English rugby union league at the eighth level of club rugby union in England involving sides based in Hampshire, Surrey and south-west London.

Relegated clubs move into either Surrey 1 or Hampshire Premier depending on their location, with sides coming up from these divisions, although only 1st XV clubs are allowed in London 3 South West.

Each year all clubs in the division also take part in the RFU Senior Vase - a level 8 national competition.

On 30 October the RFU announced [1] that a decision had been taken to cancel Adult Competitive Leagues (National League 1 and below) for the 2020/21 season meaning London 3 South West was not contested.

United Services Portsmouth who finished 5th in 2018-19 were unable to fulfil their fixtures in and withdrew from the league in November 2019.