Members of the public watching the Coronation on television, online or gathered in the open air at big screens will be asked to pledge their allegiance to King Charles in a "chorus of millions of voices" on Saturday.
Charles' ceremony will include the first Homage of the People - a modern addition that will see people across the UK and overseas realms invited to swear an oath to the new monarch.
Lambeth Palace said it was hoped the significant change to the historic service will result in a "great cry around the nation and around the world of support for the King".
It replaces the traditional Homage of Peers, in which a long line of hereditary peers knelt and made a pledge to the monarch in person.
The Archbishop will call upon "all persons of goodwill in the United Kingdom of Great Britain and Northern Ireland, and of the other realms and the territories to make their homage, in heart and voice, to their undoubted King, defender of all".
The Coronation oath in full reads: "I swear that I will pay true allegiance to Your Majesty, and to your heirs and successors according to law. So help me God."
It will be followed by the playing of a fanfare.
The Archbishop of Canterbury will then proclaim "God Save The King", with all asked to respond: "God Save King Charles. Long live King Charles. May the King live forever."
A Lambeth Palace spokesman said the homage is "very much an invitation rather than an expectation or request". People might join in if that feels right for them as they would take part in the national anthem.
He added: "It's simply an opportunity offered by the Archbishop so that, unlike previous coronations, those who wish to join in with the words being spoken by the Abbey congregation could do so in a very simple way.
"For those who do want to take part, some will want to say all the words of the homage; some might just want to say 'God Save The King' at the end; others might just want it to be a moment of private reflection."
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He added: "For those who may wish to join in with the homage, we hope it's a moment of joy and celebration - both in the abbey, and in homes around the country and beyond."
The liturgy - the words and actions of the Coronation service - has been revealed after it was chosen in consultation with the King, the Archbishop of Canterbury and the Government.
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Transport Secretary Mark Harper and Labour's national campaign co-ordinator Shabana Mahmood both told the BBC's Sunday With Laura Kuenssberg programme that they would make the pledge, while Green Party co-leader Adrian Ramsay suggested he would opt out.
Mr Harper told the programme: "When His Majesty became King most Members of Parliament actually retook the oaths that we take to His Majesty and I am very happy to do that again.
"I think the coronation is going to be a fantastic moment for the country, to bring the country together to unite around the Crown and I think a fantastic advertisement for our nation across the entire world with hundreds of dignitaries coming to the country.
"It is a big opportunity for Britain."
Ms Mahmood, an MP, added: "I think it is a lovely idea to involve the people and instead of a homage of the peers, as it used to be, it is now a homage of the people.
"Like all Members of Parliament I have already sworn my allegiance to the King.
"I am a practising Muslim, I did that on my holy book. I was very proud to do so and I will be joining in at the weekend as well."
Mr Ramsay said: "I will watch it because I think it is a key time for the nation but I think that the idea of a pledge is possibly somewhat outdated.
