Euroscepticism in the United Kingdom is a continuum of belief ranging from the opposition to certain political policies of the European Union to the complete opposition to the United Kingdom’s membership of the European Union. It has been a significant element in the politics of the United Kingdom (UK). A 2009 Eurobarometer survey of EU citizens showed support for membership of the EU was lowest in the United Kingdom, alongside Latvia and Hungary.^: 91–3

Levels of support for the EU have historically been lower in the UK than most other member states. UK citizens are the least likely to feel a sense of European identity, and national sovereignty is also seen as more important to British people than that of people from other EU nations. Additionally, the United Kingdom was the least integrated EU member state with four 'opt-outs' – the most of any EU member state.

A referendum on the UK's membership of the European Community was held in 1975, with a majority voting in favour of continued membership of the EC (which later evolved into the European Union). A referendum on membership of the EU was held in 2016, with a majority of voters voting to leave the European Union.

The decision of the electorate to vote in favour of Brexit marks the first time in history that a member state has decided to leave the European Union.