Ramage was born in Dublin, Ireland. He entered the Dublin School of Artists in 1763 and began his career as a goldsmith and miniaturist.In 1763, he studied at the Dublin Society School where he learned the art of miniature painting in watercolor on ivory. Most of his commissions were earned via portraits. In 1772, he traveled to Halifax, Nova Scotia and subsequently settled in Boston.
Ramage joined "the Loyal Irish Volunteers," a military unit defending Boston on behalf of the British Crown. His loyalty to England led him to New York City in 1777, which was occupied by Britain at the time. In debt, he travelled between New York and Halifax, troubled by bigamy and failing health due to alcoholism. He fled to Montreal in 1794 to escape further debt. He died there in 1802.