Born into the family of painter William Collins in London, he lived with his family in Italy and France as a child and learned French and Italian. He worked as a clerk for a tea merchant.
After his first novel ''Antonina'' was published in 1850, he met Charles Dickens, who became a close friend, mentor and collaborator. Some of Collins's works were first published in Dickens' journals ''All the Year Round'' and ''Household Words'' and the two collaborated on dramatic and fictional works.
Collins published his best known works in the 1860s, achieved financial stability and an international reputation. During this time he began suffering from gout took opium for pain and developed an addiction. During the 1870s and '80s the quality of his writing declined along with his health.
Collins was critical of the institution of marriage and never married; he split his time between Caroline Graves except for a 2-year separation, and his common law wife Martha Rudd with whom he had 3 children.