Isabella was born on 12 March 1409, the eldest daughter of James II, Count of Urgell, and Isabella of Aragon. Isabella was one of five children. The county of Urgell was dissolved in 1413, following her father's revolt against the new King Ferdinand I of Aragon who had been chosen to succeed to the throne of Aragon in 1412 despite James being the closest legitimate agnate to the Royal House of Aragon.
Peter of Coimbra was regent of Portugal from 1439, and engineered the marriage of his young charge, Afonso V of Portugal with his daughter, Isabella of Coimbra in 1447. But he also gathered powerful enemies, most notably the House of Braganza, who ingratiated themselves with the young king and managed to drive Peter from power immediately after. The parties remained at odds and Portugal careened into civil war. After Peter of Coimbra was killed at the Battle of Alfarrobeira in May 1449, his family was immediately and relentlessly persecuted. Isabella of Urgell and her daughter Philippa went into hiding, while her other children were driven into exile abroad - Peter the Constable to Castile, and John, James and Beatrice to the Duchy of Burgundy, the lands of their aunt Isabella of Burgundy. The threats of the powerful Duke of Burgundy were conjoined to the pleas of Peter's daughter, the young queen Isabella of Coimbra, who pleaded her husband to have mercy on her family. Against the advice of the powerful Braganzas, Afonso V relented in 1450 and allowed the widowed duchess Isabella of Urgell to reside in Montemor-o-Velho and Tentúgal. However, she continued to be harassed by the Braganzas - Afonso, Marquis of Valença reportedly tried to deprive the widowed duchess of her residence, which only the queen's renewed pleading prodded Afonso V to intercede on her behalf. Isabella of Coimbra availed of the king's good mood after the birth of their son, the royal heir John, in May 1455, to engineer a complete and final rehabilitation of the rest of her family. Peter of Coimbra's remains were allowed to be re-buried at the Aviz dynasty necropolis at Batalha Monastery and the dowager-duchess Isabella of Urgell was granted a royal pension for the remainder of her years. Isabella of Urgell died on 17 September 1459, at the monastery of Santa Cruz in Coimbra. Her remains were translated to Batalha, into the tomb of her rehabilitated husband. Her father had died while imprisoned at Xàtiva in 1433.
