Nasio was born in Rosario, Santa Fe, Argentina. After qualifying as a doctor Nasio completed his residency as a psychiatrist at the hospital in Lanús. He emigrated to France in 1969 where he worked with Jacques Lacan. He was a professor at the University of Paris VII Sorbonne for 30 years from 1971 and is considered one of the foremost commentators on Lacanian psychoanalysis. He was the first psychoanalyst to be inducted into the prestigious French Legion of Honor. In addition to participating in Lacan's seminars and translating his Écrits into Spanish, he has authored numerous books in French and Spanish, and he is the director of the Seminaires Psychanalytiques de Paris, a major center for psychoanalytical training and the dissemination of psychoanalytical thought to nonspecialists.