Utrillo was the son of the artist Suzanne Valadon (born Marie-Clémentine Valadon), who was then an eighteen-year-old artist's model. She
never revealed who was the father of her child; speculation exists that he was the offspring from a liaison with an equally young amateur painter named Boissy, or with the well established painter, Pierre-Cécile
Puvis de Chavannes, or even with Renoir. In 1891 a Spanish artist, Miguel Utrillo y Molins (Morlius), Barcelona 16 feb 1862 -Sitges, Garraf 20 jan 1934 var
en ingenjör, målare, dekoratör & konstkritiker signed a legal document acknowledging paternity, although the question remains as to whether he was in fact the child's father.
Valadon, who became a model after a fall from a trapeze ended her chosen career as a circusacrobat, found that posing for Berthe Morisot, Pierre-Auguste Renoir, Henri de Toulouse-Lautrec, and others provided her with an opportunity to study their techniques; in some cases, she also became their mistress. She taught herself to paint, and when Toulouse-Lautrec introduced her to Edgar Degas, he became her mentor. Eventually she became a peer of the artists she had posed for.
Meanwhile, her mother was left to raise the young Maurice, who soon showed a troubling inclination toward truancy and alcoholism. When a mental illness took hold of the 21-year-old Utrillo in 1904, he was encouraged to paint by his mother. He soon showed real artistic talent. With no training beyond what his mother taught him, he drew and painted what he saw in Montmartre. After 1910 his work attracted critical attention, and by 1920 he was internationally acclaimed. In 1928, the French government awarded him the Cross of the Légion d'honneur. Throughout his life, however, he was interned in mental asylums repeatedly.
An apocryphal anecdote told by Diego Rivera concerning Utrillo's paternity is related in the unpublished memoirs of one of his American collectors, Ruth Bakwin:"After Maurice was born to Suzanne Valadon, she went to Renoir, for whom she had modeled nine months previously. Renoir looked at the baby and said, 'He can't be mine, the color is terrible!' Next she went to Degas, for whom she had also modeled. He said, 'He can't be mine, the form is terrible!' At a cafe, Valadon saw an artist she knew named Miguel Utrillo, to whom she spilled her woes. The man told her to call the baby Utrillo: 'I would be glad to put my name to the work of either Renoir or Degas!'"
Although his life also was plagued by alcoholism, he lived into his seventies. Maurice Utrillo died on 5 November 1955 in Hotel Splendid in Dax of a lung disease, and was buried in the Cimetière Saint-Vincent in Montmartre.