He showed promise very early, and was a member of the Royal Academy even before he came to the public eye with a drawing entitled Caractacus, which was entered for a competition to design murals for the new Houses of Parliament at Westminster in 1848. He was best known for his portraits, including some of his wife, the actress Ellen Terry, who was nearly thirty years his junior. When she eloped with another man after less than a year of marriage, Watts was obliged to divorce her. In 1886 he re-married, to Mary Fraser Tytler, a potter.
Although Watts is associated with the Pre-Raphaelite brotherhood, his style was in general quite distinct from theirs. In 1881, having moved to London, he set up a studio at his home. Refusing the baronetcy offered him by Queen Victoria, he later moved to Compton in Surrey, where there is a gallery dedicated to his work.