By the 11th century a minster church had been established in Highworth. Minsters were almost invariably found on Saxon royal estates, and would have served the surrounding area. Highworth's church was built in the typical cruciform plan of that period and had two chapelries, or daughter churches, at South Marston and Blunsdon.
Mention of the priest is made in the Domesday survey of 1086, 'Ralph the priest holds the church of Wrde and to it belong 3 hides which did not pay geld in the time of King Edward. Land for 2 ploughs. These the priest has, with 6 bordars; meadow, 10 acres. Value 100s.' This is the estate represented in the hundred by the 'tithing of the parson of Worth'. The 1091 charter of St Osmund, Bishop of Old Sarum, shows that the chapter already held the church of Highworth and that the tithes belonged to the canons.
Warin FitzGerold the younger, hereditary chamberlain to both King Richard and King John and whose name appears on the Magna Carta, was granted the right to hold a weekly Wednesday market and an annual fair at Highworth on the feast of St Michael (29th September) by King John on the 20th April 1206. A later grant to hold an annual fair on the feast of St Peter ad Vincula (1st August) was made to his great grandson, Baldwin de Redvers, 8th Earl of Devon, by King Henry II on 12th June 1257. By the 17th century the market had become 'the greatest market for fat cattle in Wiltshire.'
Considerable profits were to be made from successful markets and annual fairs, from the granting of permanent property rights in a town and from the jurisdiction of a town court. Many lay lords, including FitzGerold, sought to create towns on their properties. Highworth was established as a planted town, possibly grafted onto an already existing small community. It formed a local market centre serving the surrounding hinterland.
It is not known exactly when Highworth became a borough. It is possible that its charter may have been granted at the same time as the one to hold markets and fairs. Certainly by 1262 Highworth is recorded as a borough with fifty tenants holding burgages or part burgages. Remnants of the linear pattern of the medieval burgage plots, long narrow strips of land, which these tenants would have held, can still be seen between the High Street and Brewery Street, and Sheep Street to Cherry Orchard. The houses on the north side of the High Street and in the centre of the market place appear to be later encroachments and infills.
By the late 13th century Highworth had corporate status becoming a parliamentary borough having the right to elect members of parliament. Medieval representation in 1298 and 1311 can be found in the parliamentary papers of that time. The town lost its privilege of sending members to parliament through disuse and the corporation has ceased to exist.
Highworth's hundred court met fourteen to sixteen times in the year, probably in its early history in the church and later elsewhere. It dealt with routine matters such as the fining of brewers against the assize, nuisances such as the flooding or obstruction of a road or the diversion of a water course, quarrels leading to bloodshed, thefts and housebreaking. The lord of Highworth hundred possessed the special liberty of the right of infangtheof, the summary hanging of a thief taken with stolen goods on him, and usually applied to experienced thieves taken at fairs and markets. The Borough and Hundred Court was held regularly up to June 1847, chiefly in latter years as a court for recovering small debts, but was eventually abolished when County Courts were formed, not withstanding a petition by local inhabitants to retain it.