John of Viseu (in Portuguese João) (ca. 1448 – 1472) was the older son of Infante Fernando, Duke of Viseu and of his wife Infanta Beatrice of Portugal.
In 1470, following his father's death, he inherited the titles of Duke of Viseu and Duke of Beja, as well as the Lordships of Covilhã and Moura
He also become Master of the Order of Christ and of the Order of Santiago, becoming also Constable of Portugal.
In July 1472, his uncle, King Afonso V granted him the Moroccan city of Anfa (in Portuguese Anafé).
He died young and single, without issue. His brother, Infante Diogo, inherited his titles and estates.