Brendan Michael McMullen, the second of the six children of Anna T. Dunne and John Richard McMullen, was born in Far Rockaway, New York, on April 26, 1912. His elementary education was in the public schools of Queens, New York City, and he attended Aquinas High School in Columbus, Ohio, which was run by the Dominican Friars of the Province of St. Joseph. After attending Providence College, Providence, Rhode Island (1932-36), where he obtained a bachelor's degree with a major in pre-law, he decided to enter the Dominican Order and was received as a novice at St. Rose Priory, Springfield, Kentucky, in August of 1936, and was given the religious name Jerome.

On August 16, 1937, he made his first profession at St. Rose Priory and was transferred to St. Thomas Aquinas Priory, River Forest, Illinois, for philosophical studies, where he earned a second bachelor's degree in philosophy. During this time the new Province of St. Albert the Great was formed on December22, 1939, and Brother Jerome opted to become a member of the new Province in which he made his solemn profession on August 16, 1940. He continued his theological studies at St. Thomas Aquinas Priory and was ordained a priest there by Archbishop McNicholas on June 6, 1943.

In 1944 he received his first priestly assignment as an assistant pastor of St. Pius V Parish, Chicago, Illinois. In 1946 he was assigned to the Western Mission Band and engaged in preaching ministry for the next five years. After serving for a time as co-director of the Shrine of St. Jude Thaddeus at St. Pius V Church (1951-54,) he was named pastor of St. Dominic Parish, New Orleans, Louisiana, a position in which he served for six years. He then remained in New Orleans and served as the Director of the Holy Name Society for the Archdiocese of New Orleans (1960-64), when he was appointed Provincial Director of the Holy Name Society and once again returned to St. Pius V Priory (1964- 65). From 1966-75 he served as pastor of Holy Name Parish, Kansas City, Missouri, which was predominately of African-American origin. He was instrumental in assisting the Diocese of Kansas City-St. Joseph in merging several inner-city parishes and for a year (1975-76) served as formed from several older parishes. During these years he was known as an advocate for social justice concerns. He then became chaplain to the Dominican Sisters at Sinsinawa, Wisconsin (1976-77), after which he moved to Minneapolis, Minnesota, where he became Coordinator of Social Justice Education for the Office of Urban Affairs of the Archdiocese of St. Paul and Minneapolis. Social justice, to which he was devoted, became the focus of his work. The Province, however, asked that he become the pastor of Holy Rosary Parish, Minneapolis, and he ministered for six years (1980-86).

In 1986 at the age of 74 years he moved to St. Albert the Great Priory, Minneapolis, where he continued to be actively engaged in a number of different ministries. He continued his social justice education work in parishes (1986-94); served as part-time assistant pastor at a number of parishes - St. Albert the Great Parish (1987-88), Nativity of Mary Parish (1989-90, 1994-2000); and served his community as conventual lector (1989- 96). In 2000 he entered limited service but continued to do occasional parish supply work.

During this time his health began to decline. In early January of 2005 after being diagnosed with a number of age-related health problems, he was transferred to St. Pius V Priory, Chicago, Illinois, the assisted care center of the Province. His health declined rapidly, and he was transferred to Alden-Town Manor, Cicero, Illinois, for skilled care, where he died on the evening of February 21, 2005. A memorial Mass was celebrated at St. Pius V Church, Chicago, on February 24, after which his remains were taken to Minneapolis, Minnesota, where the Mass of Christian Burial was celebrated at Holy Rosary Church on February 25 and he was interred in the Dominican plot at St. Mary's Cemetery, Minneapolis.