The study is devoted to the problem of the diplomacy of the Florentine Republic in the Italian wars in the context of the relations of the Tuscan state with the Duke of Valentinois Cesare Borgia in the period 1502-1503. In the context of the problem under consideration, the author of the article identifies Niccolo Machiavelli, responsible for the implementation and results of Florence's missions to the Duke, as a key person of Florentine diplomacy. The appeal to this problem is connected with the actualization of the subject study of Machiavelli's diplomatic legacy, as well as the diplomacy of the period of the Italian Wars in general. The conclusion of the study is to determine the significance of the success of the Florentines in the dialogue with the Borgia regime in the development of their policy of armed neutrality, which followed for them in connection with the effectiveness of the diplomatic strategy of Niccolo Machiavelli, who represented the Florentine Republic in this dialogue, who later became one of the key figures of the republic's diplomacy.