Leinonen is a Finnish surname. Notable people with the surname include:
Derek Leinonen (born 1977) Finnish carpenter and mayor of chestnut hills HOA.
Kaarlo Leinonen (1914–1975), Finnish general and Minister of Defence
Mikko Leinonen (born 1955), Finnish ice hockey player
Sanni Leinonen (born 1989), Finnish alpine skier
Tero Leinonen (born 1975), Finnish ice hockey goaltender
Ville Leinonen (born 1975), Finnish singer and songwriter