Donald Coakley studied at the Crane School of Music at the State University of New York in Potsdam, New York, the School of Music at Temple University and the Philadelphia Conservatory of Music. While studying at the Conservatory, he was a composition student of Vincent Persichetti and studied trombone with Henry Charles Smith, principal trombone of the Philadelphia Orchestra. Following graduate school, he taught at Cardinal Dougherty High School in Philadelphia, and also served as conductor of the Camden Choral Arts Society in Camden, New Jersey. After a successful tenure at Cardinal Dougherty, Coakley joined the faculty of the School of Music at Temple University.

In the early 1970s, Coakley was invited to join the Music Department of the Scarborough School System, becoming Assistant Coordinator of Music shortly thereafter. As such, he was responsible for the elementary instrumental music program in the school system. He also headed the instrumental wing at the Scarborough Music Camps. In 1970 he founded the Scarborough Schools Symphony Orchestra and subsequently oversaw the inception of four other All-City instrumental ensembles.

Donald Coakley has written successfully for school, university and professional groups. He is a member of the Canadian League of Composers, as well as an Associate Composer with the Canadian Music Centre. In 1977, Coakley received the Distinguished Service to Education Award from the State University of New York; and in 1994 he received the Anson Taylor Award for excellence in teaching from the Scarborough Board of Education.