Alfonso IV d'Este (2 February 1634 – 16 July 1662) was Duke of Modena and Reggio from 1658 until his death.

He was the father of Mary of Modena, consort of James II of England.

In 1655 he married Laura Martinozzi, Cardinal Mazarin's niece, thus strengthening his alliance with France.

They had two children, Maria and Francesco, who went on to become Queen of England and Duke of Modena, respectively.

In 1659 the Franco-Spanish War came to an end and Modena was rewarded with the town of Correggio for supporting France.