Isabella of Portugal (February 21, 1397 – December 17, 1471) is Duchess of Burgundy as the third wife of Duke Philip the Good.

Born a Portuguese infanta of the House of Aviz, Isabella is the only surviving daughter of King John I of Portugal and his wife Philippa of Lancaster.

Her son by Philip is Charles the Bold, the last Valois Duke of Burgundy.

Isabella is the regent of the Burgundian Low Countries during the absence of her spouse in 1432 and in 1441–1443.

She serves as her husband's representative in negotiations with England regarding trade relations in 1439 and those with the rebellious cities of Holland in 1444.