Blanche of Portugal was born on 25 February 1259 as the daughter of King Afonso III of Portugal and his second wife Beatrice of Castile. Around 1277, she went to live in the Monastery of Lorvão, but she did not take the veil or become its abbess.
She is then recorded as living in Seville with her mother in 1283, and she was even left a substantial amount of money by her maternal grandfather, King Alfonso X of Castile. In 1295, Beatrice became a nun at the Convent of Las Huelgas, despite the fact that she was reluctant to enter the order. She never the abbess but was known as the Lady and the Keeper of the convent.
Blanche never married but she did have an illegitimate son with a Portuguese nobleman named Pedro Nunes Carpenteyro or Pedro Estevanez Carpenteyro. We don’t know his exact date of birth, but perhaps this was the reason Blanche entered the Convent of Las Huelgas. His name was Juan Núñez de Prado. He was a knight of the Order of Calatrava and later became its Master. He was murdered in 1355 by the squire Diego López de Porras. He was recognised as her son in the chronicles of Alfonso XI of Castile, but this too does not record his date of birth or the circumstances leading up to his birth.
Blanche executed her will on 15 April 1321 and asked to be buried at the Convent of Las Huelgas and that 10,000 masses were to be celebrated for the good of her soul. She died just two days later on 17 April.