Catherine was married to João I, Duke of Braganza (descendant in male line from Afonso I, Duke of Braganza, an illegitimate son of King John I of Portugal), who himself was grandson of the late Duke Jaime of Braganza, also a legitimate heir of Portugal, being the son of Infanta Isabella, sister of Manuel I and daughter of Infante Ferdinand, Duke of Viseu, second son of King Duarte I.