Picker was born in New York on July 18, 1954. He started piano lessons in 1962, the same year he began corresponding with composer Gian Carlo Menotti, who was supportive of the youth's activities. Three years later, Picker was taken into the preparatory division of the Juilliard School of Music for instruction in piano and theory. He rapidly progressed and in 1972 enrolled at the Manhattan School of Music, where he studied with Charles Wuorinen (composition) and John Corigliano (orchestration). After graduating in 1976, he began taking instruction in composition from Elliott Carter at Juilliard.
Picker soon broke onto the music scene in New York with several highly successful premieres, including those of his Sextet No. 3, commissioned and performed in 1977 by Speculum Musicae, and his Rhapsody for violin and piano, premiered in 1978. Picker received two fellowships from the National Endowment of the Arts, the first coming in 1980 and the second in 1982. Three major premieres took place in 1983, including that of the Edo de Waart-led San Francisco Symphony performance of his Symphony No. 1. Picker accepted the Houston Symphony's appointment as its composer-in-residence in 1985, and in that role produced what may well be his most popular orchestral composition, Old and Lost Rivers (1986). He stepped down as composer-in-residence for the Houston Symphony in 1990 but remained steeped in commissions from other sources such as the New York Philharmonic, for which he produced his 1992 Bang!, for piano and orchestra.
Picker's music was also making headway abroad by the 1990s. His 1983 Encantadas, for actor and orchestra (on texts by Herman Melville), was performed in Tokyo by the Houston Symphony under Christoph Eschenbach. Picker also had another connection with Japan now, since he had become composer-in-residence that same year for the Pacific Music Festival in Sapporo. His compositions were also regularly appearing on concert programs in other major cities throughout the world. In Picker's boyhood correspondence with Menotti, the master had encouraged the youth to compose operas. In 1996, he finally satisfied his friend's hopes with Emmeline, written on commission from the Santa Fe Opera company, which gave the world premiere. The following year, the work was presented on the PBS Great Performances television series. Emmeline was also recorded by Albany Records. Picker continued to focus on the opera form, writing the comic opera Fantastic Mr. Fox for the Los Angles Opera and Thérèse Raquin, which was premiered by the Dallas Opera in 2001. The Metropolitan Opera commissioned Picker's fourth opera, An American Tragedy, premiering the work in 2005.
Though he was establishing himself as an opera composer, Picker has continued writing in other musical forms as well. His String Quartet No. 2 was commissioned by the American String Quartet, who premiered the work in 2009. That year, he wrote Three Nocturnes for Ursula, dedicated to pianist Ursula Oppens as was his earlier Four Etudes for Ursula. In 2010, Picker founded Opera San Antonio, and composed the ballet Awakenings, inspired by Oliver Sacks' novel. Picker served as the artistic director of Opera San Antonio from its founding until 2015 when he took up the same position with the Tulsa Opera. A 2014 recording by the Boston Modern Orchestra Project and Odyssey Opera of Fantastic Mr. Fox was issued in 2019 and earned a Grammy Award for Best Opera Recording. He returned to Sacks' work for his sixth opera, writing an Awakenings opera with a libretto by his husband, Aryeh Lev Stollman, whom he married in 2016. ~ Robert Cummings & Keith Finke, Rovi