The Batley and Spen by-election will be held on Thursday October 20, it has been announced.
Voters will go to the polls to find a successor to the late Labour MP Jo Cox who died after being attacked in Birstall in June.
By-elections have to be called within three months of the death of a sitting MP.
A writ will be moved in Parliament to confirm the date.
The Labour party in Batley and Spen has launched a search for its candidate with the deadline for nominations set for noon on Friday.
A list of candidates will be drawn up before interviews take place on Monday night.
A final shortlist will be drawn up and a candidate chosen at a hustings event in the constituency a week on Friday.
One of the favourites is believed to be former Coronation Street and EastEnders actress Tracy Brabin, a friend of Ms Cox.
Both were students at Heckmondwike Grammar School.