Nigel Farage is reportedly planning a £100,000 "Brexit Celebration Party" in Parliament Square for the night of January 31.
The Brexit Party leader is drafting arrangements for the bash, which is set to include fireworks, bands and comedians to mark the moment Britain leaves the EU, according to Prime Minister Boris Johnson's desired timetable.
"Jan 31 is a moment to celebrate, when the establishment have been beaten by the people," Mr Farage was quoted as saying by The Sunday Telegraph.
"We will invite people from all parties. Business figures will be asked to join the celebration. There will be a few short speeches but they won't be very political.
"It will be celebratory. There will be music and singing. It will be a good-natured, upbeat, optimistic, genuine celebration with no direct political edge whatsoever."
Mr Farage is applying to the Greater London Assembly - which licenses events on Parliament Square - to stage the party, the paper said.
It will be organised under the cross-party Leave Means Leave banner, with between 5,000 and 10,000 members of the public expected to attend, each paying a small ticket price to cover costs.