Bronzino was born in Florence, the son of a butcher. According to his contemporary Vasari, Bronzino was a pupil first of Raffaellino del Garbo, and then of Pontormo, to whom he was apprenticed at 14. Pontormo is thought to have introduced a portrait of Bronzino as a child (seated on a step) into one of his series on Joseph in Egypt now in the National Gallery,London. Pontormo exercised a dominant influence on Bronzino's developing style, and the two were to remain collaborators for most of the former's life. An early example of Bronzino's hand has often been detected in the Capponi Chapel in the church of Santa Felicita by the Ponte Vecchio in Florence. Pontormo designed the interior and executed the altarpiece, the masterly Deposition from the Cross and the sidewall fresco Annunciation. Bronzino apparently was assigned the frescoes on the dome, which however have not survived. Of the four empanelled tondi or roundels depicting each of the evangelists, two were said by Vasari to have been painted by Bronzino. His style however is so similar to his master's that scholars still debate the specific attributions.
Towards the end of his life, Bronzino took a prominent part in the activities of the Florentine Accademia delle Arti del Disegno, of which he was a founding member in 1563.
The painter Alessandro Allori was his favourite pupil, and Bronzino was living in the Allori family house at the time of his death in Florence in 1572 (Alessandro was also the father of Cristofano Allori). Bronzino spent the majority of his career in Florence.