This research investigates how the Brazilian State instrumentalized Bossa Nova as a cultural diplomacy tool between 1960 and 1970, with particular focus on the emblematic Carnegie Hall concert (1962). Through documentary analysis of diplomatic archives, period publications, and specialized bibliographic sources, the study examines the institutional mechanisms through which Itamaraty and other government agencies systematized the international projection of the musical genre as a soft power vehicle. The research demonstrates that the Brazilian State developed a deliberate strategy operationalized through three main mechanisms: direct and indirect financing of international performances and tours; coordination between different ministries and government agencies, especially the partnership with the Brazilian Coffee Institute; and mobilization of the Brazilian diplomatic network to facilitate and amplify the international reach of the musical movement. However, the analysis reveals that this instrumentalization was partial, contradictory, and vulnerable to political changes, especially after the 1964 military coup, when a structural dissonance emerged between the image of modernity and sophistication projected internationally and the internal authoritarian reality. The study contributes to the fields of International Relations History and Cultural Studies by demonstrating how cultural elements can be strategically mobilized in foreign policy, offering relevant lessons for understanding contemporary cultural diplomacy practices in the digital era.