Osmo Heikki Kristian Soininvaara (born 2 September 1951 in Helsinki) is a Finnish politician and writer, former party leader and cabinet member.

He was elected in Eduskunta in 1987 and again in 1995 and was a member of parliament until 2007, when he chose not to stand for re-election.

He was the leader of the Finnish Green League party from 2001 to 2005.

Soininvaara is a long-time advocate of a basic income and has published several books and reports on this topic.

as the best economics book of 1994, he proposed a detailed basic income scheme differentiated for household composition.