Oxfordshire ( / ˈ ɒ k s f ər d ʃ ər / or / ˈ ɒ k s f ər d ʃ ɪər /; archaically the County of Oxford; abbreviated Oxon from the Latinised form of "Oxford", Oxonia) is a county in the South East England region, bordering on Northamptonshire (to the north/northeast), Buckinghamshire (to the east), Berkshire (to the south), Wiltshire and Swindon (to the southwest), Gloucestershire (to the west) and Warwickshire (to the north).

It is divided into five local government districts: Oxford, Cherwell, Vale of White Horse (after the Uffington White Horse), West Oxfordshire and South Oxfordshire.

The county has a major tourist industry. The area is noted for the concentration of performance motorsport companies and facilities. Oxford University Press is largest firm among a concentration of print and publishing firms; the University of Oxford is also linked to the concentration of local biotechnology companies.

The main centre of population is the city of Oxford. Other significant settlements are Banbury, Bicester, Kidlington, and Chipping Norton to the north of Oxford; Witney to the west; Thame and Chinnor to the east; and Abingdon, Wantage, Didcot, Wallingford and Henley-on-Thames to the south. Future population growth in the county is hoped to be concentrated around Oxford, Banbury, Bicester, Didcot and Witney, near the South Midlands growth area.

The highest point of the administrative county is White Horse Hill, in the Vale of White Horse, reaching 261 metres (856 ft). The highest point in the historic county is near Portobello Farm in the Chiltern Hills at 255 metres.

Oxfordshire's county flower is the Snake's-head Fritillary.