The Sinn Fein vice president will attend the ceremony along with her party’s Stormont Assembly Speaker Alex Maskey.
Sinn Fein’s Michelle O’Neill has insisted her attendance at the King’s coronation is “more than just a gesture” and demonstrates her commitment to reconciliation.
The party’s vice president said she was attending the ceremony because it is the “right thing to do” in terms of promoting a shared future in Northern Ireland.
The republican leader and Sinn Fein’s Assembly speaker Alex Maskey have both accepted invitations to the coronation in London.
The move is the latest signal of vastly improved relations between the republican movement and the Royal family since the outset of the peace process.
Ms O’Neill, who attended the Queen’s funeral service in September, is in line to become Northern Ireland’s first minister if the current powersharing impasse is resolved and devolution returns in Belfast.
She has repeatedly pledged to be a “first minister for all”.
“I think at this juncture it’s important that I demonstrate and fulfil my commitment to be that First Minister for all and attend the coronation to represent all of our community,” she told the PA news agency.
“I’m comfortable enough in my own skin and I think that it’s important that at times like this that I demonstrate by words and deeds that I will be the first minister for all, I will represent everybody in our community.”
She added: “We are living in a time of great change. A time to respect our differing and equally legitimate aspirations, a time to firmly focus on the future and the opportunities that the next decade will bring.
“I am an Irish republican.
“I also recognise there are many people on our island for whom the coronation is a hugely important occasion.”
Ms O’Neill said her eyes were “very much focused on the future”.
“That has to be about reconciling our people,” she added.
“So that’s why in moments like this it’s very important that, particularly for myself as a first minister for all and somebody who feels that I can represent everybody in our community, that I reach out and that I do something that actually demonstrates my commitment to bring forward a better society for everybody.
“Because I’m determined to look to the future, I’m determined to look at the next 10 years and 20 years and what that means for our island, the people who share this island, and the relationships between our two islands.
“So, I think reconciliation is still something that we all need to be pushing ourselves on and making sure that we do everything that we can to reconcile all the people across these two islands.”
She added: “I think that it’s important that all of us in political leadership reach out that hand of friendship.
“I don’t do what I do for reciprocation, I do what I do because I believe in it, I believe it’s the right thing to do and I believe in fulfilling the promises that I make.
“So the ‘first minister for all’ is much more than a gesture for me, it is actually following through in terms of everything that I do.
“So, for me, this is a juncture at which I hope that will be received in the way in which is intended, which is that I will represent everybody and then I am determined to build a better future into the decades ahead for everybody that lives here and shares this place as their home.”