Portomaggiore (Ferrarese: Portmagiòr) is a town and comune in the province of Ferrara, Emilia-Romagna, Italy.

In the Battle of Portomaggiore of 1395, mercenary troops of the Ferrara Regency Council, assisted by allies from Florence, Bologna, and Venice and fighting in the name of the young Niccolò III d'Este, Marquis of Ferrara beat the rebel forces of his uncle, Azzo X d'Este, pretender to the Lordship of Ferrara.

[3] The main attraction of the comune is the Delizia del Verginese, in the frazione of Gambulaga, a castle-residence built by Duke Alfonso I d'Este in the early 16th century.

Also remarkable is the church of San Giorgio, Gambulaga.

Davide Santon, a former footballer and Marcella Tonioli, an Italian compound archer, were born in Portamaggiore.