At the age of 28, he began studying singing at the Hochschule für Musik und Tanz Köln with Else Bischof.
He made his stage debut in 1974 at the Theater Aachen in the role of Monterone in Verdi's Rigoletto, stepping in for an ill singer.
From 1975 to 1977, he was engaged as a chorus singer at the Aachen Opera House, where he also performed small solo parts.
He worked at the Aachen theatre until 1980 and was subsequently engaged for three years at the Badisches Staatstheater Karlsruhe, to which he later belonged as a permanent guest.
[1] Welker has been a member of the Hamburgische Staatsoper since 1982, the Vienna State Opera since 1985 and the Deutsche Oper Berlin since 1987.