List of United Kingdom by-elections (2010–present)

This is a list of parliamentary by-elections in the United Kingdom since 2010, with the names of the incumbent and victor and their respective parties. Where seats changed political party at the election, the result is highlighted: blue for a Conservative gain, red for a Labour gain, orange for a Liberal Democrat gain, purple for a UKIP gain and other colours for any other gains.

, a total of 59 by-elections have been held in this period. The first was held in January 2011 and the most recent in May 2024.

Process of resignation from the House of Commons
Where the cause of by-election is given as "resignation" or "seeks re-election", this indicates that the incumbent was appointed on his or her own request to an "office of profit under the Crown", either the Steward of the Chiltern Hundreds or the Steward of the Manor of Northstead. Accepting an office of profit under the Crown vacates the member's seat. This process is used because members of the House of Commons are not technically permitted to resign. A member who vacates their seat in this manner may stand for re-election.

Recall petition
A recall petition is created by advice of the Speaker of the House of Commons if an MP is suspended from the House for at least 10 sitting days, usually a result of a criminal conviction or breaking Commons Select Committee on Standards conventions. A petition is successful if at least 10 per cent of the constituency's electorate sign the petition. Successful petitions result in the MP vacating the seat, triggering a by-election.

As of March 2024, six petitions have been held under the Act, four resulting in by-elections and one being terminated early due to the MP's resignation.

2024–present Parliament
There have not yet been any by-elections scheduled in the current Parliament.

2019–2024 Parliament
The 2019–2024 Parliament included 23 by-elections, the most by-elections in one parliament since the 1987–1992 Parliament, which had 24. Fourteen by-elections occurred in constituencies previously represented by the governing Conservatives, seven in constituencies represented by Labour, and two in constituencies represented by the SNP. The incumbent MP's party won nine by-elections, including one at Southend West, in which the other major parties did not field candidates. Labour won thirteen by-elections, gaining seven seats from the Conservatives and one from the SNP, but losing one each to the Conservatives and the Workers Party of Britain. The Liberal Democrats gained four seats from the Conservatives, while the Conservatives gained one from Labour. Five by-elections happened due to the deaths of the incumbent MPs, three of whom represented the Conservatives and two Labour.

2017–2019 Parliament
There were five by-elections in the 2017–2019 Parliament, which was the smallest number since the six-month parliament that sat between the two general elections in February and October 1974. Three were in seats held by Labour, one by the governing Conservatives and one by Sinn Féin, who do not take up their seats in the House of Commons. Four by-elections were won by the incumbent party and the Liberal Democrats won a seat from Conservatives. One by-election was a result of the death of the incumbent MP, who represented Labour. Two by-elections were the result of recall petitions via the provisions of the Recall of MPs Act 2015, the first such in the country.

At the dissolution of Parliament in 2019 there were two vacancies: Bassetlaw, caused by the resignations of Labour member John Mann, and Buckingham, caused by the resignation of Speaker John Bercow. With the proximity of the 2019 general election, by-elections were not called for these seats. The Conservatives, the party Bercow had represented before he took up the speakership, regained Buckingham and won Bassetlaw from Labour as well.

2015–2017 Parliament
There were ten by-elections in the 2015–2017 Parliament (with a planned by-election in Manchester Gorton cancelled when the 2017 general election was called). Seven were in seats held by Labour, and three by the governing Conservatives. Eight by-elections were won by the incumbent party: the Conservatives won a seat from Labour and lost one to the Liberal Democrats. Three by-elections happened due to the deaths of the incumbent MPs, all of whom represented Labour.

At the dissolution of Parliament in 2017, one seat was vacant: that for Manchester Gorton, caused by the death of its Labour member Gerald Kaufman. With the close proximity of the 2017 general election on 8 June, the by-election previously called for 4 May had its writ cancelled by the House of Commons. All but two of the candidates nominated for the by-election then stood at the general election, and Labour held the seat.

2010–2015 Parliament
There were 21 by-elections in the 2010–2015 Parliament. Fourteen were in constituencies held by Labour, four by the governing Conservatives, one by their coalition partners the Liberal Democrats and two by Sinn Féin, who do not take up their seats in the House of Commons. Seventeen by-elections were won by the incumbent party: Labour won a seat from the Conservatives and lost one to Respect, while UKIP gained two seats from the Conservatives after the incumbent MPs defected to the party and were re-elected. Six by-elections happened due to the deaths of the incumbent MPs, all of whom represented Labour. In all six of those by-elections, Labour retained the seat.