Moreira Salles implemented a series of successful acquisitions and an emphasis on human resources, helping to make Unibanco one of Brazil's top three banking institutions.

In 1990-91 Moreira Salles launched the Moreira Salles Institute (IMS), a nonprofit organization whose goal is to promote the development of cultural projects in five areas: photography, literature, libraries, visual arts and Brazilian music.

[2] He was Secretary of the Treasury in the cabinet of João Goulart, and gained the favour of President Juscelino Kubitschek for his work as a conciliator in his diplomatic incursions.

In the 1950s he helped negotiate the growing problem of Brazil's external debt on three occasions, during the governments of Getúlio Vargas, Kubitschek and Jânio Quadros.

Moreira Salles had many celebrity friends, including the rock musician Mick Jagger, Brazilian President Fernando Henrique Cardoso, and the actress Greta Garbo.