Carmen Posadas was born on 13 August 1953 in Montevideo, Uruguay. Her father was a diplomat and in her youth the family lived in Uruguay, London, Russia, and Madrid. She began a course at university but dropped out in the first year to get married. She had two daughters from this first marriage and later remarried to Mariano Rubio, the former director of the Banco de España, and became part of the Spanish "jet-set". She started off her literary career by writing children's books. She produced about 10 books of stories and tales for children and was rewarded with a prize from the Ministerio de Cultura for the best children's book in 1984. In 1986, she produced her first book of a different genre and since then has tried many styles: she has written essays, plays, novels and short stories. She also presented a television show in the late 1980's and has collaborated to the writing of television and cinema scripts.

She has obtained Spanish nationality and currently lives in Madrid .