Jaakko Mäntyjärvi (born 1963) is a Finnish composer of classical music, and a professional translator.
Mäntyjärvi was born in Turku. He studied musicology, English philology and linguistics at the University of Helsinki, graduating with an FK (master's) degree in 1991. In 1987, he was accredited as an Authorized Translator from Finnish to English and English to Finnish, and since then he has been employed as a professional translator. He has also studied theory of music and choir conducting at the Sibelius Academy.