Matthias Leja was born in Lüneburg. He studied at the Hochschule für Musik und Theater in Hamburg, during which time he gave guest performances at Schauspiel Frankfurt. Following his graduation, he joined ensembles in Cologne, Düsseldorf, Bochum and Hamburg. In 1987, Leja was voted Best Emerging Male Actor in Hesse. In 2007, he was awarded the Gustaf Award by Düsseldorf audiences for Best Male Actor. He can be seen in numerous television productions, and has lent his voice to audiobooks. Leja joined the Schauspiel Stuttgart ensemble in the 2018/19 season.