Cooley studied at the Philadelphia Musical Academy with Frederick Hahn and Camille Zeckwer, and later with Percy Goetschius and Louis Svečenski at the Institute of Musical Art (Juilliard School) in New York City.
He was Principal Violist of the NBC Symphony Orchestra from 1937 to 1954 during the years of Arturo Toscanini's tenure.
In 1954, upon Toscanini's retirement, Cooley joined the Philadelphia Orchestra viola section under Eugene Ormandy and was appointed Principal Violist in 1956, succeeding Harry Zaratzian.
Cooley was married to Ada Eleanor Strother (b. Liverpool UK 1886, d. Flemington NJ 1986) from August 26, 1923 until his death in November 1981.
He is the grandfather of fiction writer Martha Cooley (b. NJ 1955), whose novels include "The Archivist" and "Thirty Three Swoons"; attorney Seth van den Hoek Cooley (b. NJ 1957): children Ian David Cooley (b. PA 1987), Hannah Claire Cooley (b. PA 1989) and Benjamin Trevorrow Cooley (b. PA 1993); and archivist Karen Cooley Boysen (b. NJ 1962): children Cyril van den Hoek Boysen (b. CA 1992) and Aartdina Parry Boysen (b. CA 1995).