The Cologne-born Metternich made his Covent Garden debut in 1951, in The Flying Dutchman, and was the first German to debut at the Metropolitan Opera in an Italian role, as Don Carlos in La forza del destino, in 1953. He stayed with the Met until 1956.
At the height of his career, Metternich was performing 150 times per year, with contracts that bound him to opera houses in East and West Berlin, Vienna, Hamburg, and Munich. He also performed at La Scala, the Op_ra de Paris, and the Edinburgh Festival.
Metternich was also a singing coach, and gave classes in Cologne and Munich.
He retired in 1971, after a 35-year career.