Rishi Sunak will vow to "fulfil the promise of the Good Friday Agreement" by bringing jobs and investment to Northern Ireland.
In a closing speech at the Agreement 25 Conference in Belfast, the prime minister will hail the 1998 peace deal as one of the most extraordinary political achievements in recent history.
He will say the best way to protect its "precious legacy" is to make good on a commitment to create jobs and opportunities for young people in Northern Ireland.
"Together we must fulfil the true promise of the 1998 Agreement", he will tell an audience of global leaders at Queen’s University.
"That future enshrined in the very words of the text – of ‘sustained economic growth’, and where we tackle the problems of ‘a divided society’.
"And I will give everything to help deliver that vision.
"BGFA [Belfast Good Friday Agreement] promised prosperity and a more integrated society and we have work to do to deliver on that promise."
The speech at a gala dinner on Wednesday will round off the recent period of prime minister-led commemorations marking the 25th anniversary of the signing of the BGFA.
The treaty, signed by former Labour prime minister Sir Tony Blair and former Irish PM Bertie Ahern, and partly brokered by the US, helped stem the sectarian bloodshed of the Troubles that had blighted Northern Ireland for decades.
Following concessions made on both sides during the negotiations, the BGFA created powersharing institutions at Stormont that involved nationalists and unionists governing the region together in a mandatory coalition arrangement.
While the pact largely ended the Troubles, which had claimed more than 3,600 lives since the late 1960s, it has failed to bring long-term political stability in the region and devolution has collapsed several times in the last two decades.
The 25th anniversary comes amid another period of collapse, with the DUP blocking powersharing in protest at post-Brexit trading arrangements that have created economic barriers between Northern Ireland and Great Britain.
Having negotiated the Windsor Agreement with the European Union to ease those trade frictions and restore power sharing, Downing Street said Mr Sunak will address his economic ambitions for Northern Ireland.
He will say: "I know that journey to prosperity won’t be easy – and we aren’t there yet. But this is my commitment to you:
"I will use the full force of the UK government to help you make this one of the best places in the world to start and grow a business, create jobs, train and learn new skills, and attract investment."
During his dinner speech, which former prime ministers Boris Johnson and Liz Truss are expected to attend, Mr Sunak will also herald those who helped bring about the agreement a quarter of a century ago.
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"Courage, imagination, and perseverance – those qualities brought an imperfect but enduring peace to a place taught to believe no such peace was possible," Mr Sunak will say.
"To all those who led us to that peace, including those here in this hall and those no longer with us – let us take this moment to say to you: thank you."
Having met US President Joe Biden in Northern Ireland last week, Mr Sunak will speak to architects of the Good Friday Agreement at the gala dinner, along with Irish and US representatives.
The dinner will be attended by political leaders, international dignitaries and leading charities, No 10 said.
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