 Widmer was born in Zürich and studied first under his father, the baritone Kurt Widmer, at the City of Basel Music Academy.He made his debut as a recitalist in 1985 followed by further study under Dietrich Fischer-Dieskau at the Hochschule für Musik Berlin from 1986 to 1989.He has been a member of the Zurich Opera from the early 1990s.