John Joseph Mulcahy (June 26, 1922 – April 29, 1994) was a Roman Catholic bishop.

Born in Dorchester, Massachusetts, Mulcahy was ordained to the priesthood on May 1, 1947, for the Roman Catholic Archdiocese of Boston. On December 28, 1974, Mulcahy was appointed titular bishop of Penafiel and auxiliary bishop of the Boston Archdiocese and was ordained on February 11, 1975. He resigned on July 21, 1992.^[1]