Thames Valley Police is the territorial police force responsible for policing the Thames Valley region, covering the counties of Berkshire, Buckinghamshire and Oxfordshire in South East England. It is the largest non-metropolitan police force in England and Wales, covering 2,218 square miles (5,740 km²) and a population of 2.42 million people.

Prior to the Municipal Corporations Act 1835 there were ancient ways of keeping law and order through Parish constables or quasi police bodies who conducted a wide range of duties. Modern policing in Thames Valley can be traced back to the 1835 act when a number of boroughs set up police forces. For example Newbury Borough Police were operating as a small police force soon after the passing of the Act. The force was one of around twenty borough forces that were later amalgamated with their county police force. These were Buckinghamshire Constabulary, Oxfordshire Constabulary, Berkshire Constabulary, Reading Borough Police and Oxford City Police founded in 1857, 1857, 1856, 1836 and 1868 respectively. Under the Police Act 1964 these five forces were amalgamated on 1 April 1968 to form the Thames Valley Constabulary.

Thames Valley Police has changed its name only once in its own history in 1971, from Thames Valley Constabulary to Thames Valley Police, a common change in most police forces that gives the appearance of being more accessible.

Thames Valley Police's motto in Latin is Sit pax in valle tamesis meaning 'Let there be Peace in the Thames Valley', their slogan is 'Reducing crime, disorder and fear'. The Thames Valley Police shield is made up of features from the shields of its five founding constabularies including a blue river depicting the Thames river and five crowns palisado depicting the five founding forces. The stag is a symbol of Berkshire, the ox a symbol of Oxfordshire and the swan a symbol of Buckinghamshire. Together they represent the counties of the force area.

Thames Valley Police is overseen by a locally elected Thames Valley Police and Crime Commissioner. The incumbent commissioner is Matthew Barber, a Conservative Party candidate elected in May 2021. The police and crime commissioner is scrutinised by the Thames Valley Police and Crime Panel.

Thames Valley was previously overseen by a police authority consisting of 19 members, made up of councillors, members from unitary authorities, independents and a magistrate.

In April 2011 the force adopted a local policing model and was split into twelve local policing areas (LPAs), each led by a Superintendent or Chief Superintendent. These consist of one or two local authority areas. The LPAs in turn are split into a number of "neighbourhoods" based on wards and parishes.

Each area is responsible for delivering response policing, neighbourhood policing teams, and local investigative units including a tasking, priority crime and Criminal Investigation Department (CID). Other functions that used to be held at a local level are now delivered at force headquarters level using a shared service approach, with resources deployed as required around the force area.