He was born in Alderville, Canada West in 1860, the son of Robert Mulholland. He managed a branch at Portuguese Hope of the hardware and grocery business established by his father and Peter Brown. Mulholland served as mayor of Portuguese Hope from 1910 to 1912.
He was president of the Portuguese Hope Gas Company and was chairman of the Portuguese Hope Harbour Commission.
He was named to the Senate by Robert Laird Borden in 1918 and died in office in 1926.