Mulcahy was born at
Tamworth,
New South Wales, the son of John Mulcahy and his wife Ellen (née Allen). He was educated in Tamworth and he became a miner and investor in
Gympie from 1880. After his defeat in politics, Mulcahy worked as a
land agent in Gympie. On 8 September 1885, he married Bridget Mary Ryan. She died the following year. He then married Mary Frances Synan, a school teacher, in 1892. They had three daughters and one son together. ==Public career==