Davies was born in Toledo, Ohio, on April 16, 1944. His formal training includes studies at the Juilliard School of Music, where his conducting teachers were Jean Morel and Jorge Mester. He made his conducting debut in 1968, leading the Juilliard Ensemble in performances at the Spoleto Festival. In 1969, Davies led the same group (under the name "The Ensemble") in the famed concert series "New and Newer Music" at Lincoln Center. In 1970, he led the premiere performance of Luciano Berio's opera Opera at the Santa Fe Festival. Davies' first appointment was as the music director of the Norwalk Symphony (1968-1973). From 1972 to 1980, he was the music director of the Saint Paul Chamber Orchestra and, from 1974, director of the Cabrillo Music Festival. Davies made his European operatic debut with a production of Debussy's Pelléas et Mélisande at the Netherlands Opera in 1973. In 1977, he was a founding member and the music director of the American Composers Orchestra, a New York ensemble specializing in new music. His tenure with that ensemble, which continued until 2001, represents one of the longest such associations on the American orchestral scene. In 1978, Davies became the second American (after Thomas Schippers) to be asked to conduct at the Wagner Festival in Bayreuth, where he led performances of The Flying Dutchman through 1980. Davies held the post of music director of the Württemburg State Theater in Stuttgart from 1980 to 1987. There, in addition to premiering works like Henze's The English Cat, Glass' Akhnaten, and Bolcom's Songs of Innocence and Experience, he attracted attention for controversial productions of more familiar repertoire.
Davies has lived in Germany since 1980, although he spends much of his professional life in the United States. From 1991 until 1996, he was the director of the Brooklyn Academy of Music and principal conductor of the Brooklyn Philharmonic. He debuted at the Metropolitan Opera in 1996, conducting the premiere of Glass' The Voyage. In the 1990s, he also premiered Berio's Un re in ascolto at the Chicago Lyric Opera and Schwertsik's operetta Der ewige Frieden in Bonn and Vienna. Davies was the chief conductor of the Stuttgart Chamber Orchestra from 1995 until 2006. In 2002, he took on the chief conductor position of both the Linz Opera and the Bruckner Orchestra Linz. He was also named the music director of the Sinfonieorchester Basel in 2008. In 2017, in celebration of Glass' 80th birthday, Davies conducted the premiere of the composer's Symphony No. 11. In 2018, he became the chief conductor for the Filharmonie Brno, and in 2020, he assumed the same role for the MDR-Sinfonieorchester in Leipzig.
Davies is amply represented on recordings, especially of new music. His label associations include projects with Nonesuch, ECM, Point, Argo, Tzadik, MusicMasters, and CRI. His recordings include a complete survey of Haydn's Symphonies with the Stuttgart Chamber Orchestra, Glass: Waiting for the Barbarians, Schnittke: Symphony No. 9, Essential Beethoven, and Glass: Symphony No. 9. In 2020, Davies, conducting the Wiener Singakademie, the ORF Vienna Radio Symphony Orchestra, and featuring Vojtech Dyk, was heard on a recording of Bernstein's Mass. ~ Rovi Staff, Rovi