The 2009–10 South West Peninsula League season was the third in the history of the South West Peninsula League, a football competition in England, that feeds the Premier Division of the Western Football League.
The league had been formed in 2007 from the merger of the Devon County League and the South Western League, and is restricted to clubs based in Cornwall and Devon.
The champions for the first time in their history were Buckland Athletic.
The Premier Division featured 20 teams, the same as the previous season.
Two new clubs joined the league after Newton Abbot were expelled and Newton Abbot Spurs were relegated to Division One East: