Born in Feuchtwangen, Bavaria, Karg studied at the Mozarteum, voice with Heiner Hopfner and Lied with Wolfgang Holzmair.

Karg made her debut at the Salzburg Festival in 2006, as Melia in Mozart's Apollo et Hyacinthus and as Weltgeist in his Die Schuldigkeit des ersten Gebots.

A year later she appeared there as Madame Silberklang in his Der Schauspieldirektor and in a title role of his Bastien und Bastienne.

[2][3][4] From the 2008/09 season, Karg was a member of the Frankfurt Opera where she appeared as Susanna in Mozart's Le nozze di Figaro, as Pamina in his Die Zauberflöte, as Musetta in Puccini's La bohème, Zdenka in Arabella by Richard Strauss, and the title role in Debussy's Pelléas et Mélisande.

[2] She performed the solo soprano part in Mahler's Second Symphony in a performance of the Rheingau Musik Festival 2017 at Eberbach Abbey, conducted by Christoph Eschenbach, with Gerhild Romberger, the SWR Vokalensemble, Chor des Bayerischen Rundfunks [Wikidata] and SWR Symphonieorchester.