Kehrer was born in Dessau and completed his vocal studies in Berlin. He had early engagements at Chemnitz opera house, Aalto-Theater Essen and in Valencia. In 2012/2013 he joined the ensemble of Deutsche Oper Berlin. There he sang, among other roles, Sarastro Die Zauberflöte, Masetto and Commendatore Don Giovanni, Basilio Il barbiere di Siviglia, Sparafucile Rigoletto, the Monk Don Carlo, Zuniga Carmen, Fafner Das Rheingold and Siegfried, Orest Elektra, Colline La Bohème, Narbal Les Troyens, Ratcliffe Billy Budd, Daland Der fliegende Holländer, Gremin Eugene Onegin.
He has also sung at the New York Metropolitan Opera - Sarastro Die Zauberflöte - , at Salzburg Festival (Police Inspector in Der Rosenkavalier and Truffaldin in Ariadne auf Naxos), at Glyndebourne-Festival (Osmin Die Entführung aus dem Serail ), Bayerische Staatsoper (Osmin), Lyric Opera of Chicago (Fafner), Opéra National de Paris (Sarastro), Teatro alla Scala (Osmin) and Bayreuth Festival (Titurel, Nightwatchman, Hunding).
Current and upcoming engagements include – apart from his performances in Berlin – stints in Munich and Bayreuth.