He was son of the Catalan writer Joaquin Nin Tudó and Àngela Castellanos Perdomo, a Cuban from Camagüey.

[2] Nin studied piano with Moritz Moszkowski and composition at the Schola Cantorum (where he taught from 1906 to 1908).

Joaquín Nin appears as one of the characters in the novel The Island of Eternal Love (Riverhead, 2008), by Cuban writer Daína Chaviano.

In her memoirs and fiction, his daughter Anaïs Nin often attempts to consider aspects of her own nature by recalling how her father treated her as a child.

Her "unexpurgated" diary volume Incest: From a Journal of Love describes an incestuous relationship with him in adulthood.