Count McCormack was born in Athlone, Ireland, the fourth of eleven children of Andrew McCormack and Hannah Watson[5] on 14 June 1884, and was baptised in St. Mary's Church, Athlone on 23 June 1884. His parents were employed at the Athlone Woollen Mills.
McCormack received his early education from the Marist Brothers in Athlone, and he later attended Summerhill College, Sligo. In 1903 he won the coveted gold medal of the Dublin Feis Ceoil. He married Lily Foley in 1906 and they had two children, Cyril and Gwen.
In March 1904, McCormack became associated with James Joyce, who at the time had singing ambitions himself. Richard Ellmann, in his biography of Joyce, states that, "Joyce spent several evenings with him" (i.e. McCormack), practising; along with Joyce's acquaintance Richard Best, McCormack persuaded Joyce to enter the Feis Ceoil that year.