The Sacristy, which was built as the Chapel of the Annunciation by the Cavalcanti family in 1380 on the site of the apse of the primitive church of Santa Maria delle Vigne, can be found at the point where the transept meets the lefthand nave. Today this part of the church is really a museum. The cupboards were designed by Bernardo Buontalenti in 1593 while, on the right of the door, the large lavabo enclosed by an aedicula of glazed terracotta, can be included among the many masterpieces by Giovanni della Robbia (1498).

The walls are hung with paintings by the 16th and 17th century Florentine school Giorgio Vasari, Giovanni Strada, Pietro Dandini...), though the most important work of all is a Christ on the cross, carried out by Giotto in his youth, which was once above the high altar of the church (it is at present being restored in the workshops of the Opificio of Semi-precious Stones). Here, a century before their rediscovery, this great master applied the rules of the proportions that had been established by the Roman architect Vitruvius (I century A.D.): in fact, when the point of the compass is placed on the navel of the human body, the drawn circle will be found to pass through both the hands and the feet.