He was born in Geneva to a French mother and an English father, and grew up mainly in France and Italy. In 1882, after the death of his parents, he studied art at the City and Guilds Technical Art School in Lambeth. There he met Charles Shannon, painter and lithographer, who became his lifelong partner in both his artistic and personal life. Ricketts and Shannon lived together at The Vale, Chelsea, and founded the Vale Press, named after their house.
Ricketts and Shannon were friends and supporters of Oscar Wilde, and Ricketts illustrated some of Wilde's books. Ricketts also became well known as a set and costume designer for the theatre.