Walter Robertson was born in Ireland, and was likely the son of a Dublin goldsmith. Both he and his younger brother Charles became miniaturists. He studied at Dublin Society Schools and exhibited miniatures at the Society of Artists in Dublin from 1769-1775 and 1777. He moved to London in c. 1784, but returned bankrupt to Dublin in 1792. Robertson decided to sail for America in 1793 with his friend and fellow artist Gilbert Stuart. Settling in Philadelphia, Robertson painted miniature copies of Stuart’s portraits, along with his own original miniatures of George Washington. He is sometimes referred to as the Irish Robertson, to distinguish him from the Scottish miniaturists Archibald, Andrew, and Alexander Robertson. He left America after 1796 for India, where he died.