Collins was born in Great Titchfield Street, London, son of William Collins Sr., an Irish-born picture-dealer and writer. He showed a great aptitude for art from an early age, and was for a while an informal pupil of George Morland. In 1807, he entered the schools of the Royal Academy (at the same time as William Etty), and exhibited at the Academy for the first time in the same year. In 1809 he was awarded a medal in the life school, and exhibited three pictures\: "Boy at Breakfast", "Boys with a Bird's-nest" and a "Portrait of Master Lee as he spoke the Prologue at the Haymarket Theatre".