Juana was born on 28 February 1462 in Madrid as Juana of Castile, the daughter of Queen Juana of Portugal and King Enrique IV. She was nicknamed “La Beltraneja” due to doubts about her parentage. A part of the nobility, including Juan Pacheco, claimed that Beltrán de la Cueva — not King Enrique — was her real father.

On 9 May 1462, she was proclaimed Princesa de Asturias and heir to the throne in the Iglesia de San Pedro el Viejo in Madrid. Later, because of those questions about her parentage, she would be forced to relinquish both the title of Princess of Asturias and her claim to the throne in favour of Isabel.

After the death of her father, Enrique IV, her aunt Isabel declared herself queen, leading to a civil war — the so-called War of the Castilian Succession — in which the indecisive Battle of Toro became one of the most significant confrontations.

After losing the war, she lived in exile in Portugal, where she was known as “a Excelente Senhora”.

She died on 12 April 1530 in Lisbon.