A religious community was established at Westminster by about 960, when King Edgar and Saint Dunstan supported a Benedictine house on Thorney Island beside the Thames. The monastery's fortunes changed under Edward the Confessor, who chose the site for a large Romanesque church linked to his royal palace. Consecrated in December 1065, shortly before Edward's death, it became his burial place. Only traces of that building survive, but its association with the king helped make Westminster a focus of royal devotion and government.

William the Conqueror was crowned in the abbey on Christmas Day 1066, beginning a coronation tradition followed by nearly every English and later British monarch. In 1245 Henry III ordered a new church in the Gothic style, inspired partly by major French cathedrals and intended as a fitting shrine for Edward the Confessor. The choir, transepts, chapter house, and eastern chapels rose during Henry's reign. Their pointed arches, rib vaults, sculptural program, and unusually tall proportions made the abbey one of medieval England's most ambitious royal buildings.

Construction and alteration continued for centuries. The nave was completed largely in the late fourteenth and early fifteenth centuries, while Henry VII added his elaborate Lady Chapel from 1503. The Dissolution of the Monasteries ended the Benedictine community in 1540. Westminster briefly became a cathedral, returned to monastic use under Mary I, and in 1560 Elizabeth I refounded it as a collegiate church answerable directly to the sovereign. That status, known as a Royal Peculiar, continues today.

The abbey accumulated royal tombs, aristocratic monuments, and memorials to people prominent in national life. Poets' Corner developed around Geoffrey Chaucer's burial, while scientists, musicians, politicians, soldiers, and public servants were later buried or commemorated throughout the church. Royal weddings, jubilees, funerals, and coronations reinforced its public role. During the Second World War, staff protected movable treasures and fought incendiary fires; bombing damaged the roof and surrounding precinct, but the main medieval structure survived.

Modern conservation treats Westminster Abbey as both a living church and a layered historic monument. Archaeology, stone repair, environmental monitoring, and specialist care for tombs, sculpture, paintings, glass, textiles, and manuscripts are carried out while daily worship and public visiting continue. The Queen's Diamond Jubilee Galleries opened in the medieval triforium in 2018, displaying objects from the abbey's history without displacing its religious functions. Together with the Palace of Westminster and St Margaret's Church, the abbey was inscribed as a UNESCO World Heritage Site in 1987.