Romney was born at Beckside near Dalton in Furness.
In 1755, he was apprenticed for four years to Christopher Steele, a travelling portrait painter.
Some time in 1757, however, he ended his apprenticeship with Steele by a friendly agreement and began to work on his own in Kendal, Cumbria.
Romney eventually moved to London in 1762. He visited Italy and established himself as a fashionable portraitist, rivalling the success of Sir Joshua Reynolds and Thomas Gainsborough.
Although he also executed historical works, he is best known for his remarkable portraits.