Campos left New York City for Brazil in 1949. From 1951 to 1953, he acted as an economic advisor in the second Getúlio Vargas administration, whose hallmarks were the paramountcy of nationalist economic policies. He was one of the supporters of the creation the BNDES, a public authority whose function was to supply emerging industries with low-interest and long-term credits. After Vargas's suicide, Campos served as economic advisor to his elected successor, president Juscelino Kubitschek. During the 1950s and early 1960s, Campos presented himself as a promoter of "pragmatic, democratic nationalism," as when he tried, as Brazilian ambassador in Washington, to reach an understanding between the John Kennedy administration and the left-leaning João Goulart government. Eventually, disagreements with Goulart's policies led to his resignation in August 1963. Roberto Campos sided with the military regime installed by the 1964 coup, which was greatly backed by Jorge Flores, a business partner of his. The first military president, Marshall Castelo Branco, appointed Campos as his Minister of Planning — and chief economic policy maker, jointly with the Finance MinisterOctavio Gouvea de Bulhões — in which capacity he enacted various pro-business and pro-foreign capital — as well as anti-organized-labour — reforms that aimed to modernize the Brazilian economy in a liberal sense. His sympathies for an inconditional pro-American foreign policy and foreign-capital-friendly economic policies earned him, already during the 1960s, his lifelong sobriquet: "Bob Fields". During the late 1960s and 1970s, he disagreed with the increasing amount of state intervention in the economy included in the process of authoritarian modernization achieved by later military administrations and remained at the sidelines, working mostly as an adviser in private enterprise. In 1975, he was appointed Brazilian ambassador to the United Kingdom, remaining in this office for nearly seven years. At the demise of the dictatorship, he regained political influence and became a politician in his own right. In 1980, soon after the end of the two-party regime, he joined the newly formed pro-government PDS. Two years later, he won the election for an eight-year term as senator for his native state of Mato Grosso. As a member of the electoral college in the 1985 presidential election, he voted for the defeated PDS candidate, Paulo Maluf. Starting in 1991, he served as federal deputy for the State of Rio de Janeiro during two legislatures. In 1998, he was defeated when trying to return to the senate, thus ending his political career.
At the end of his life he tended to portray himself as solitary liberal, fighting against what he called "leftist" governments and policies, becoming one of the most vocal opponents of socialism in Brazil. His 1994 autobiography A lanterna na popa revises his personal biography — as well as the recent economic history of Brazil — according to this vein. In 1999, he was elected member of the Brazilian Academy of Letters by a thin margin of four votes. He died of heart attack on 9 October 2001 at his apartment in Rio de Janeiro. His papers reside at the Universidade Positivo. He was married with two sons and one daughter.
