On 5 May 2011, a by-election was held for the UK House of Commons constituency of Leicester South. It was prompted by the resignation of Sir Peter Soulsby of the Labour Party, who stood down from Parliament to contest the election for Mayor of Leicester. Soulsby was appointed Crown Steward and Bailiff of the Manor of Northstead on 1 April 2011, and the writ for a new election was issued on 5 April. The election was won by Labour Party candidate Jon Ashworth.

Leicester South is a constituency, recreated in 1974, represented in the House of Commons of the UK Parliament since 2011 by Jonathan Ashworth of the Labour Co-op Party. A previous version of the seat existed between 1918 and 1950. Except for a 2004 by-election when it was won by the Liberal Democrats, Leicester South has been held by the Labour Party since 1987.