Blanche was born on 6 July 1387 as the second eldest daughter of Charles III of Navarre and Eleanor of Castile. She was one of eight siblings, and Blanche became the heiress of Navarre upon the death of her eldest sister, Joan, who had been married to John I, Count of Foix. She married for the first time to Martin the Younger, King of Sicily and Prince of Aragon. They married by proxy on 21 May 1402 and in person on 26 December 1402. He was 13 years older than she was. They had a single son, also named Martin who lived for just a year. Her husband died on 25 July 1409 and Blanche remained widowed for ten years, though several betrothals were arranged to Louis of Bavaria-Ingolstadt (brother of the French Queen Isabeau of Bavaria) and Edward of Bar. She remained in Sicily as regent, finally leaving in April 1415 for Navarre. She was sworn in as heiress of the Kingdom of Navarre on 28 October 1416 by a parliament held at Olite.
She finally married again by proxy on 6 November 1419 to John, Duke of Peñafiel, who was the second son of Ferdinand I of Aragon and Eleanor of Alburquerque. On 10 June 1420, the two finally met in person and married in Pamplona. In five years time, they had four children, of which the second died young. Her father Charles died on 8 September 1425 and Blanche succeeded him as Queen regnant of Navarre, with John as its suo jure King.
Blanche died in Santa María la Real de Nieva in 1441. After her death, John kept the government of Navarre under his control, refusing to hand it over to their son Charles, the rightful King of Navarre. He was eventually taken prisoner by his father and never yielded any true power. He died suddenly on 23 September 1461 of suspected poisoning. Her daughter Blanche succeeded her brother as the rightful Queen of Navarre as Queen Blanche II. She had been married to Henry IV of Castile, but that marriage had been annulled in 1453 due to non-consummation. She was sent home to Navarre, where she imprisoned by her family. She remained childless, and died in 1464, probably also by poisoning. This paved the way for the succession of her youngest sister Eleanor, who wisely did not cross her father and only pressed her claim after his death in 1479.
Queen Blanche I’s husband later remarried to Juana Enriquez and with her, he fathered the future Ferdinand II of Aragon, who married the Queen regnant of Castile, Isabella. Blanche is buried in the Nuestra Señora de la Soterraña church in Santa María la Real de Nieva in Spain.