Les Landes-Genusson () is a commune in the Vendée department in the Pays de la Loire region in western France.
Les Landes-Genusson has an oceanic climate (Köppen climate classification Cfb). The average annual temperature in Les Landes-Genusson is . The average annual rainfall is with November as the wettest month. The temperatures are highest on average in August, at around , and lowest in January, at around . The highest temperature ever recorded in Les Landes-Genusson was on 5 August 2003; the coldest temperature ever recorded was on 1 March 2005.