Bedwyn lies beside the River Dun, close to a Roman road between Winchester and Cirencester. About a mile to the north is the Iron Age hill-fort of Chisbury, suspected as having been one of the burhs listed in the Burghal Hidage of the tenth century; its function was mainly defensive, though availability of a refuge would have encouraged the growth of a market centre nearby. Bedwyn is mentioned in land grants of Anglo-Saxon kings, the earliest dating to 778, and appears to be the focal point of an early example of a large royal estate. In Domesday it was a borough with 25 burgesses, which had the obligation of hosting the king and his retinue for one night a year – a requirement that may be indicative of Bedwyn having had some role in royal administration. Such an obligation would suggest a sizable community and the same could be inferred from late tenth century annotations in a copy of the gospels, known as the Bedwyn Bible, referring to statutes of a gild assumed to have been in Bedwyn; the existence of such a manuscript suggests the presence of a minster church. The Bishop of Winchester had purchased land there around 905 with the intent of building a church, but we know no more about this; the church mentioned in Domesday is assumed to have been a minster. A community with a gild – whose surviving statutes suggest a socio-religious character – might possibly have been urban, and further support for urban status comes from the presence of a mint in the reign of Athelstan, also mentioned in Domesday, though transferred in 1068 to Marlborough, the regional town favoured by the Normans. In 1281 Great Bedwyn was listed as the chief settlement of Kinwardstone Hundred, which was named after the meeting-place of the hundred, on the border of Great Bedwyn parish.

Long-standing borough status would explain the absence of a market licence (unnecessary) until 1468, when a Monday market and two fairs (in late March and September) were granted – the market might represent an additional market day, or point to an attempt to revitalize the local economy. Presence of a market has documentary confirmation in the 1270s, when the town was referred to as Chipping Bedwyn, the prefix (whence the modern 'shopping') pointing to its role as a market town. The 1307 inquisition post mortem on a member of the Clare family, which had acquired Bedwyn in the thirteenth century, refers to it as a villa mercatoria where market rights included not only toll but also chepyngavel; the latter, found in several Wiltshire towns, was, in Reading at least, an annual fee of a few pence paid by each of its burgesses for licence to trade toll-free in any market owned by the abbey, and at Cirencester a slightly smaller fee payable twice a year by residents for the right to trade freely in the abbey's market there.

Despite this, the Poll tax of 1377 indicates Bedwyn as the least prosperous town in the county, with only 87 tax-payers, perhaps reflecting a decline that continued in the next century and beyond. Bedwyn likely lost out to nearby markets in Marlborough and Hungerford (in neighbouring Berkshire) – better-positioned on communication routes, and expanding – with Ramsbury not much farther off. In the post-medieval period Great Bedwyn's economy seems based purely on rural trades. That economy had probably always been dependent on agriculture, including wool production; some cloth-making is evidenced in the Late Middle Ages, thought it was of a coarse, cheap cloth.

The parish church, at the south end of Bedwyn borough close to the river, came into the hands of Salisbury cathedral in 1091, along with an adjacent area as a small prebendal manor, possibly echoing the estate of a Saxon minster; the church was rebuilt in the twelfth century and improved in the thirteenth. Further north was the site of the market, held in a triangular-shaped stretch of the High Street, its wide base at a crossroads whose southern arm led past the church; the High Street was earlier known as Chipping Street or Cheap Street, and progressed eastward to a crossing of the Dun. We need not doubt that the marketplace was the focal point of the borough, and it has been conjectured that the north-south crossroad might have been the older through-road, around which early settlement developed; tenement plots reminiscent of burgages are more in evidence along that road – notably the southern stretch down to the church – than along the High Street, although later redevelopment may have obscured burgage boundaries there. It has been argued that Bedwyn was developed in a planned fashion during the Late Saxon period, beginning with a transfer of population from Chisbury, in the form of a grid layout of properties around a crossroads [the arguments are summarized in John Baker and Stuart Brookes, Beyond the Burghal Hidage: Anglo-Saxon Civil Defence in the Viking Age, Leiden: Brill, 2013, pp.229-30].