Debretzeni was born in Cluj-Napoca, in the Transylvania region of Romania, on February 24, 1971. She studied violin at the Liceul de Muzica "Sigismund Toduta" in Cluj-Napoca, until she was 15 when she moved to Israel. There she worked with violinist Ora Shiran, and she then went on for Baroque violin lessons at the Royal College of Music in London with Walter Reiter and Catherine Mackintosh. In 1997, she joined two of Britain's leading historical-performance groups: the English Baroque Soloists, led by John Eliot Gardiner, and the Orchestra of the Age of Enlightenment. Within three years, Debretzeni had become the leader of the former, and she participated prominently in Gardiner's Bach Cantata Pilgrimage and its associated series of recordings made in churches with which Bach himself had been associated. In 2008, she was named one of three rotating leaders of the Orchestra of the Age of Enlightenment. With that group, she directed an innovative 2013 choreographic presentation of Vivaldi's Four Seasons violin concertos, as well as a 2017 concert with famed mezzo-soprano Dame Sarah Connolly.
These ongoing responsibilities did not keep Debretzeni from embarking on a variety of other collaborations. She guest-directed groups in Israel, Canada, Poland, and Iceland, among other countries. Debretzeni conducts many top English and continental European ensembles, including the English Concert, the Akademie für alte Musik, and the Budapest Bach Ensemble. Between 1998 and 2003, she performed with the Amsterdam Baroque Orchestra under Ton Koopman in another complete cycle of Bach's cantatas. Debretzeni is a co-founder of the chamber group Ricordo, which specializes in the so-called stylus phantasticus of the 17th century. With these various groups, she has amassed a substantial discography, and she has also issued several solo albums. In 2019, she was heard as a soloist with the English Baroque Soloists under Gardiner on a recording of Bach's violin concertos. Debretzeni teaches Baroque and Classical violin at the Royal Conservatory of Music in The Hague. ~ James Manheim, Rovi