Olli Rahnasto (born 28 December 1965) is a retired professional tennis player from Finland.
Rahnasto turned pro in 1982. During his career, he won two ATP Tour doubles titles and reached a career high doubles ranking of No. 79 in 1986. He was a member of the Finland Davis Cup team, and led the team to the World Group Qualifying round in 1990. He retired in 1995.