Egwin's foundation grew slowly into a Benedictine house of unusual richness. The story of its survival through the Norman Conquest hinges on Abbot Aethelwig, who in 1066 read the political weather quickly and made his peace with William the Conqueror before the new king's soldiers reached Worcestershire. The abbey kept its lands. By the high Middle Ages it was one of the wealthiest in England. Pilgrims came to honour the relics of Saint Egwin, Saint Credan, Saint Wigstan of Mercia, and the Frisian missionary Saint Odulf, whose body had been brought to Evesham in the 11th century. Successive abbots built and rebuilt: a great church with twin towers, a chapter house, an almonry, an enormous gatehouse on Merstow Green, and the bell tower of Abbot Clement Lichfield, completed in the 1530s on the very eve of dissolution.

Simon de Montfort, 6th Earl of Leicester, was the leader of the baronial revolt against Henry III. He had won at Lewes the previous year, captured the king, and ruled England in all but name through a parliament that included, for the first time, elected representatives from the towns. By the summer of 1265 his support was draining away. Trapped inside a bend of the Avon at Evesham, his army half the size of his enemy's, he watched the royalist banners approach and is said to have remarked: 'God have mercy on our souls, for our bodies are theirs.' The future Edward I had ordered twelve picked men, led by the Marcher baron Roger Mortimer, to find de Montfort and kill him personally. They did. His son Henry de Montfort died first, then Simon himself, dismounted and surrounded. Roger Mortimer struck the killing blow. After the battle his body was mutilated; his head was sent to Mortimer's wife at Wigmore Castle. The monks of Evesham gathered what they could and buried him near the high altar. Within weeks pilgrims were coming to the grave.

England had killed Simon de Montfort. England then began to venerate him. Within months of the battle, accounts of miracles at the abbey grave were being copied between monasteries. The crown was alarmed enough to forbid the cult by royal decree; the cult continued in defiance. He was never formally canonised, and the church's official ledger always recorded him as a rebel - but for the better part of a century, ordinary people prayed to Earl Simon as a saint. Henry de Montfort was buried beside him. Today an altar-like memorial slab, dedicated in 1965 by the Archbishop of Canterbury on the seven-hundredth anniversary of the battle, marks the place. The high altar is gone; the building above it is gone; the slab lies on the open grass of what is now a public park.

In 1540 the abbey surrendered to the Crown's commissioners during Henry VIII's dissolution of the monasteries. They demolished it with the thoroughness applied to most of the great Benedictine houses. The church, the cloisters, the dormitories, the refectory - all came down for their lead and dressed stone. Only Clement Lichfield's bell tower was spared, possibly because it had only just been built and the demolition crew ran out of time or appetite. The tower stands 110 feet high above the precinct today, a Grade I listed object so striking that J. M. W. Turner came in 1793 to paint it and the parish church beyond, framing one through the arched opening of the other. Edward Rudge spent two decades from 1811 digging up the abbey foundations; his finds were published in Vetusta Monumenta with watercolours by his wife Anne.

Walk the precinct now and the great spaces are marked in low stone outlines on the lawn: here the nave, here the transepts, here the chapter house, here the high altar with its memorial slab. The 14th-century gateway survives, incorporated into a house at 53 and 54 Merstow Green. Abbot Reginald's wall, parts of which date to around 1120, still divides the park from the road. The 15th-century almonry is a museum now. In 2017 the Evesham Abbey Trust took ownership of much of the site, and a £1m grant from the National Lottery Heritage Fund paid for conservation work and a set of interpretive gardens completed in 2023. Eight bells still ring from Clement Lichfield's tower, the largest weighing nearly 26 hundredweight, sounding the note D across the Avon meadows.