Reijo Lahtinen studied at the Sibelius Academy in Helsinki under Jolanda di Maria Petris, Matti Tuloisela and Pekka Salomaa and at the Tampere School of Music under Matti Vihtonen. He has also studied with Matti Hannula and Jaakko Ryhänen. Reijo Lahtinen furthered his opera studies in Italy.
Reijo Lahtinen has performed almost 60 different roles with the Tampere Opera since 1960. He has guested with the Finnish National Opera, the Savonlinna Opera Festival, the Ilmajoki Music Festival and in Vaasa and Pori Opera productions, and he has performed numerous song and speech roles in theatre and television productions. In addition to his performances in Finland, he has performed as a concert soloist in Estonia, the United States and Canada.