Isabella received a comprehensive Renaissance education influenced by the works of Christine de Pizan.

In 1441, Pedro arranged the betrothal of Isabella and Afonso V.[3] Their engagement caused a conflict between Peter of Coimbra and Duke Afonso of Braganza, who had wished for the monarch to marry his granddaughter.

[3] Isabella was given the income of Santarém, Alvaiázere, Sintra and Torres Vedras at her wedding.

Isabella's father rebelled and was killed in the Battle of Alfarrobeira in 1449,[6] and her brothers John and James were exiled.

Isabella herself did not fall out of favour with the king, however, and she took control of the duchy of Coimbra until her brother John returned to Portugal in 1454.