Mella was born Nicanor McPartland in 1903 in Havana. His father was Nicanor Mella Breá (1851–1929), a tailor and son of Matías Ramón Mella Castillo, one of the heroes of the Dominican Republican war of independence. Mella's mother was Cecilia McPartland, daughter of Irish immigrants. Although Cecilia was not married to Nicanor senior, they initially named Mella after his father. As children, Nicanor Mella and his younger brother Cecilio went to New Orleans with their mother while she convalesced from lung troubles. Later the boys returned to Cuba to live with their father's wife Mercedes Bermúdez Ferreira. She acted as their stepmother. At that time, Mells's name was changed from Nicanor to Antonio, and his younger brother was renamed as Nicasio Mella.