The Belgian soprano Sophie Karthäuser has been called a born Mozartian, but she attained that status through training and experience, not birth. With some exceptions, Mozart and Haydn are at the chronological tail end of her repertoire, and she has been ideally situated as historical-instrument ensembles and conductors have moved into Classical-era repertory and beyond. Karthäuser was born in 1974 in Malmedy, in Walloon, Belgium. She wanted to emulate her older sister, a clarinetist in a regional orchestra, and, since she was still a small child, she was given lessons on the easier recorder before moving on to clarinet. Karthäuser also sang in a local church choir and gradually started to move toward vocal music, beginning lessons at 16 with Belgian teachers and making a commitment due to the twin stimuli of winning Belgium's Förderpreis and a scholarship to Britain's Guildhall School of Music.
At Guildhall Karthäuser studied with soprano Noelle Barker, whose orientation was toward contemporary music, and took some private lessons with the legendary Elisabeth Schwarzkopf in great old age. But Karthäuser gravitated toward the Baroque and Classical eras. Her operatic debut came as Pamina in Mozart's Die Zauberflöte at the Alte Oper in Frankfurt, and after graduating from Guildhall she found herself in demand from such conductors as William Christie (for whom she sang the role of Susanna in Le nozze di Figaro), René Jacobs (several roles including Polissena in Handel's Radamisto), Emmanuelle Haïm (Charpentier's Medée at the Théâtre des Champs Elysées in Paris), and many others. A fixture of Baroque opera stages in the 2000s and 2010s, Karthäuser joined Jacobs for a multi-venue touring performance of Haydn's Die Schöpfung during the 2015-2016 season.
After winning the audience prize at the Wigmore Hall Song Competition in 2003, Karthäuser also experienced expanding success as a recitalist, performing with a variety of accompanists including Eugene Asti. Karthäuser's recitals and song recordings tended toward later eras than those of her orchestral concert appearances; she released an album of Poulenc songs and, in 2016, Kennst du das Land?, a collection, with Asti, of songs by Hugo Wolf. Her recordings of Baroque music, often quite adventurous, have been honored with prizes: an album of arias by André Grétry earned a Diapason découverte, and one of Michel Richard de Lalande's weighty Leçons de Ténèbres with Sébastien Daucé and his Ensemble Correspondances won the prestigious Diapason d'Or.