The protest, which is likely to be the biggest since the 2016 vote to leave the European Union, will culminate outside Parliament, where campaigners will launch a nationwide petition for a "People's Vote".
It takes place on the two year anniversary of the referendum and amid ongoing uncertainty over the outcome of the Brexit process.
The demonstration is being organised by the People's Vote umbrella group, which encompasses a number of organisations campaigning against Brexit. They are demanding a public vote on the eventual deal that Theresa May agrees with Brussels.
The event will include speeches by a number of people from across the UK, including farmers, doctors, students, military veterans and fishermen.
The People's Vote said this represents a shift in their campaign away from Westminster and towards building public support for a second referendum.
They are planning a “Summer of Action” with events across the country designed to foster opposition to Brexit and put pressure on the government to give the public more of a say.
The speakers will appear alongside Tory MP Anna Soubry, Labour’s David Lammy, Liberal Democrat leader Sir Vince Cable and Green Party co-leader Caroline Lucas.
MPs are expected to vote on the final Brexit deal in the autumn, with the government having repeatedly insisted that leaving the EU without a withdrawal agreement remains a possibility.
Ahead of the march, Femi Oluwole, founder of the "Our Future, Our Choice" youth movement, said: “People marching on Saturday are terrified that their futures and their kids’ futures might be written in a Brexit deal negotiated by the likes of Theresa May, David Davis and Boris Johnson.
“We didn’t trust the establishment in 2016. No blooming way are we going to trust them with this. The People’s Vote March is the start of a national campaign that moves beyond Parliament and reminds people they have every right to keep
He will be joined at the protest by Brigadier Stephen Goodall, a 96-year-old Second World War veteran who is travelling from Devon to take part.
Mr Goodall said: “When I look at the politicians in Westminster who are now so recklessly seeking to sever some ties for their own narrow purposes, I feel a sense of shame and despair.”
And James Wilson, a mussel farmer from Wales who will also be attending, said: “As a fisherman, my business relies on selling live mussels to countries across the EU. A bad Brexit deal could mean my mussels are dead by the time they reach my customers.”
One van delivery driver attending the march has already offered to take the final petition to Downing Street.
Ciaran Donovan, 42, from Romford, said: “The time has come for people, not just politicians, to find their voice and make it heard. My business and my livelihood are at risk from decisions being taken in Westminster by political leaders who neither care nor understand ordinary people like me.
“The national petition for a People’s Vote on the final Brexit deal will begin on Saturday, will be taken to every street in the country and then delivered back to Downing Street. Tell you what, I’ll even deliver it there myself in my van.”
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