The county is bordered by Northamptonshire and Warwickshire to the north, Buckinghamshire to the east, Berkshire to the south, and Wiltshire and Gloucestershire to the west.

The lowlands in the centre of the county are crossed by the River Thames and its tributaries, the valleys of which are separated by low hills.

Although it had some significance as an area of valuable agricultural land in the centre of the country, it was largely ignored by the Romans and did not grow in importance until the formation of a settlement at Oxford in the 8th century.

The university in the county town of Oxford (whose name came from Anglo-Saxon Oxenaford = "ford for oxen") grew in importance during the Middle Ages and early modern period.

[citation needed] Nevertheless, Oxfordshire remains a very agricultural county by land use, with a lower population than neighbouring Berkshire and Buckinghamshire, which are both smaller.

During most of its history, the county was partitioned as fourteen divisions called hundreds, namely Bampton, Banbury, Binfield, Bloxham, Bullingdon, Chadlington, Dorchester, Ewelme, Langtree, Lewknor, Pyrton, Ploughley, Thame and Wootton.

The Vale of White Horse district and parts of the South Oxfordshire administrative district south of the River Thames were historically part of Berkshire, but, in 1974, Abingdon, Didcot, Faringdon, Wallingford and Wantage were added to the administrative county of Oxfordshire under the Local Government Act 1972.

Long-distance walks within the county include the Ridgeway National Trail, Macmillan Way, Oxfordshire Way and the D’Arcy Dalton Way.

From the mid-point western edge to the southeast corner of Oxfordshire, via the city in the middle, runs the Thames with its flat floodplains.

Oxfordshire contains a green belt area that fully envelops the city of Oxford and extends for some miles to protect surrounding towns and villages from inappropriate development and urban growth.

The county is divided into five local government districts: Oxford, Cherwell, Vale of White Horse (after the Uffington White Horse), West Oxfordshire and South Oxfordshire, which deal with such matters as town and country planning, waste collection and housing.

Chastleton House, on the Gloucestershire and Warwickshire borders, is a great country mansion built on property bought from Robert Catesby, who was one of the men involved in the Gunpowder Plot with Guy Fawkes.