Nigro moved with his family to Livorno in 1929. He graduated in chemistry and pharmacology at the University of Pisa, in 1940 and 1947 respectively, while also studying music and painting. He worked as a pharmacologist but began to focus more systematically on art in 1948. Having joined the Movimento d’Arte Concreta after an initial post-Cubist period, he moved to Milan in 1949 and held his first solo show at the Libreria Salto. He worked in the field of abstract art from the late 1940s on, producing a number of different series, and took part in the Salon des Réalités Nouvelles in Paris in 1951. He abandoned his career in pharmacology in 1958 and moved to Milan. It was through the intervention of Lucio Fontana that his participation in the Venice Biennale began by invitation in 1964 with the 32nd Esposizione Internazionale d’Arte della Città di Venezia and continued in 1968, when the dedication of a room exclusively to his work established his reputation at the international level.