Alessandro Pieroni (Impruneta, 18 April 1550 – Livorno, 24 July 1607) was an Italian architect and painter. He was active mainly in a Mannerist style, working for the courts of Grandukes Francesco I and Ferdinando I de' Medici, Grand Duke of Tuscany.
Also known as the Sandrino dall’ Impruneta. He began his career as an assistant to Alessandro Allori. Allori led the team between 1587 and 1591, including Pieroni, Giovanni Bizelli, Giovanni Maria Butteri, and a young Cigoli in decorating the ceilings of the corridors of the Uffizi in Florence.
For the chapel of San Giovan Gualberto in the Abbey of San Michele in Passignano, Pieroni painted an altarpiece of San Giovan Gualberto pardons the murderers of his brother before the crucifix of San Miniato.
For the visit of Grand-Duke Ferdinand to Pisa in 1588, Pieroni completed, along with the painter Filippo Paladino, a canvas for the church of the Santo Stefano dei Cavalieri, depicting scenes from the life of Santo Stefano Martire. He also helped design the facade. Giorgio Vasari likely also participated in the design of the ceiling decorations. He painted an altarpiece for the Principi Chapel in the church of San Lorenzo.
An artist in the court was commissioned works to celebrate the weddings of the Medici. In 1589, he was among the artists engaged in the elaborate decorations to celebrate the marriage of Ferdinando I and Cristina di Lorraine, painting the Defeat of Gian Galeazzo Visconti at Mantua. With Bernardo Buontalenti, he also made scenography for the Theater at the Uffizi, for the 1600 presentation of the comedy La Pellegrina and also made decorations to celebrate the wedding of Marie de' Medici to Henry IV of France.