2019 European Parliament election in the United Kingdom

The 2019 European Parliament election was the United Kingdom's component of the 2019 European Parliament election. It was held on Thursday 23 May 2019 and the results announced on Sunday 26 and Monday 27 May 2019, after all the other EU countries had voted. This was the United Kingdom's final participation in a European Parliament election before leaving the European Union on 31 January 2020; it was also the last election to be held under the provisions of the European Parliamentary Elections Act 2002 before its repeal under the European Union (Withdrawal) Act 2018, and was the first European election in the United Kingdom since 1999 to be held on a day that did not coincide with any local elections. This was the first of two national elections held in the United Kingdom in 2019; the 2019 general election occurred six-and-a-half months later in December 2019.

At first no European Parliament election was planned in the United Kingdom, for Brexit (following the 2016 referendum) was set to take place on 29 March 2019. However, at the European summit on 11 April 2019, the British government and the European Council agreed to delay British withdrawal until 31 October 2019. From that time onward it was the default position in UK and EU law for the election to take place; however, the UK Government continued making attempts to avoid participation by seeking agreement on a withdrawal to take place before 23 May. On 7 May 2019, the UK government conceded, despite its opposition, that the election would have to go ahead.

The election was the ninth time the United Kingdom had elected MEPs to the European Parliament (and the fourth for Gibraltar). Candidate nominations were submitted by 16:00 on 25 April 2019, and voter registration was completed on 7 May 2019. The British MEPs sat until 31 January 2020.

Brexit was the central issue of the election campaign; arguments were made that it was a proxy for a second Brexit referendum. The election was won by the Brexit Party, which won the most votes and became the largest single national party in the European Parliament, being the dominant choice of those who had voted to leave the European Union. The votes of those who had voted to remain were more fragmented: the Liberal Democrats made substantial gains, finishing second nationally, while the Scottish National Party (SNP) and the Green Party of England and Wales also improved on their results from the 2014 election; however, Change UK failed to win any seats. The Conservative Party lost all but four of its MEPs, while the Labour Party too suffered heavy losses. The previously dominant UK Independence Party failed to elect any MEPs.

In Northern Ireland, the Republican pro-Remain Sinn Féin and the Unionist pro-Leave Democratic Unionist Party both held their seats, while the Ulster Unionist Party lost its seat to the pro-Remain non-sectarian Alliance Party. In Scotland, the SNP elected three MEPs, while Labour lost both its MEPs and failed to win a seat in Scotland at a European election for the first time in its history. In Wales, the Brexit Party became the largest party, while the nationalist, pro-Remain Plaid Cymru came second. The Liberal Democrats became the largest party in London.

The election was the first national poll in the United Kingdom since December 1910 in which a successor party to the Liberal Party reached higher than third place in the number of votes or seats, and the first ever national election in which the Conservative Party received less than 10% of the votes cast.