In 1943, he moved to Rio de Janeiro to enroll in law school, while also working for the literary supplements as a professional journalist.

The death of Mário de Andrade in 1945 led to a generational change in Brazilian poetry whose rule was "an invitation to transgression", with the triumph of purely poetical structures.

He continued with O Caminho sem Adventura (1948), O sobrinho do General (1964) and Ninho de cobras (published in English as Snake's Nest) (1973), one of his biggest successes, an allegory of totalitarianism of the military dictatorship of Getúlio Vargas.

In 1949 Ivo spoke at the Museum of Modern Art of São Paulo in a conference titled The Generation of 1945; in the same year he received a degree in law, a profession he would never exercise, preferring to devote himself to journalism.

He published two memoirs, Confissões de um Poeta (1979), which was awarded the prize of the Cultural Foundation of the Federal District, and O Aluno Relapso (1991).