The province of Arezzo derives from the ancient compartment of the Grand Duchy of Tuscany. It was born in 1826 with the union of municipalities that were already part of the Florence and Siena Compartments. With the Unification of Italy in 1860 the municipalities of Cetona, Chianciano Terme, Chiusi, Montepulciano, Sarteano, Sinalunga, and Torrita di Siena were ceded to the province of Siena.
In 1927 the municipalities of Monte Santa Maria Tiberina and Monterchi were transferred the province of Perugia in Umbria. The latter was returned to the province of Arezzo in 1939 following popular discontent.
The province of Arezzo is crossed by the Arno River from its source up to San Giovanni Valdarno. The higher relief is Monte Falco with its 1658 meters, located at the north of the province in the valley of Casentino.