Walter Beckett was born in Dublin. He studied organ and harmony under George Hewson and John F. Larchet at the the Royal Irish Academy of Music. He received his Mus.B in 1936 and his Mus.D. degree from Trinity College, Dublin, in 1945. He was appointed Professor of Harmony and Counterpoint at the Royal Irish Academy of Music in the early 1970s.
Walter Beckett wrote many arrangements for the Radio Éireann Light Orchestra and Singers during the 1940s. His original works include the Suite for Orchestra, written in 1945; the songcycle Goldenhair written in 1980 with text by James Joyce; a string quartet; Irish Rhapsody for orchestra; and Falaingin Dances for orchestra. Dr Beckett was music critic of the Irish Times from 1946 to 1952.