According to Giorgio Vasari, the sculpture was made by Baccio Bandinelli, in competition with his rival Benvenuto Cellini. The two sculptors were commissioned by Cosimo I to produce his portrait in bronze as proof of their respective abilities. For Baccio, this was his chance to regain the appraisal of the Grand Duke, who had not been happy with one of his previous portraits, commissioned for Palazzo Vecchio.
The first payments for the fusion of the bust can be dated to September 1557. A few months later, the sculptor expressed his satisfaction regarding the beauty of the portrait in a letter addressed to Eleonora da Toledo; however, he also reported that the bust had been damaged due to a fall, and that it would not be possible to deliver it within a short time. He referred that he would need to intervene once more in order to adjust the “positioning”.
Even though this was not the first time Baccio had reproduced the image of the Grand Duke, in this work in particular the physiognomy of the portrait is surpassed by the sculptor’s attempt to place the figure in a precise historical and cultural context. He created the bust bearing in mind the ancient statuary tradition and it aims to show that the Medici family belonged to a historical past characterized by civil and politic virtues. Cosimo is presented as a leader with a firm and proud expression; he is wearing a piece of armor portraying two griffins facing one another, symbolizing protection, perhaps a reference to the protection guaranteed to the city of Florence by the Medici family.