MPs in the British parliament have voted overwhelmingly to endorse the so-called "Stormont Brake" - part of the wider deal between the UK and the EU on Northern Ireland.
The measure passed easily, 515 votes to 29 due to Labour support.
Both the DUP and elements of the European Research Group of Tory MPs opposed the measure but were not enough to block it.
The SDLP's Colum Eastwood said his party was supporting it despite reservations. Alliance MP Stephen Farry also voted in favour.
The vote on the brake mechanism is also being interpreted as an indicative vote by the Commons on the wider Windsor Framework - the latest EU/UK deal to resolve issues in the Northern Ireland Protocol.
It clears the way for its adoption by the UK/EU Joint Committee when it meets in London on Friday.
British Prime Minister Rishi Sunak agreed with the EU to introduce the "Stormont brake", aimed at offering Northern Ireland more control over whether to accept any new EU laws, as part of the so-called Windsor Framework of measures to soothe post-Brexit tensions.
Ahead of the vote, Mr Sunak and his ministers urged MPs to support the brake.
"The Stormont brake is at the heart of the (Windsor) Framework," Northern Ireland Secretary Chris Heaton-Harris told the Commons.
"It restores practical sovereignty for the United Kingdom as a whole and the people of northern Ireland in particular."
The ERG has described the measure as "practically useless" and the DUP complains that it does not apply to existing EU law.
Northern Ireland minister Steve Baker said the government would not be relying on opposition MPs to win the vote.
Speaking to reporters, he also addressed arguments made by allies of Mr Johnson and Ms Truss that the Northern Ireland Protocol Bill - legislation that would have unilaterally overwritten parts of the Brexit treaty with Brussels - should not have been dropped.
"The Protocol Bill would have put in place a red and a green channel for goods going to Northern Ireland," he said.
"But in using that bill, we would wreck our relations with the European Union and damage our standing internationally.
"Now that was a price we were willing to pay to get just the kind of arrangements we now have in the Windsor Framework," Mr Baker said, as he urged the pair to vote with the government.
Windsor Framework: Is this time different?
DUP leader Jeffrey Donaldson has said he is still not prepared to restore power-sharing at Stormont.
He made the comments in a social media post as MPs gathered to debate the Stormont brake.
"I have consistently indicated that fundamental problems remain notwithstanding progress made.
"Consequently there is not a sustainable basis at this stage to enable us to restore Stormont."
Mr Donaldson said he was still seeking further clarification on its operation from the British government.
SDLP MPs Colum Eastwood and Claire Hanna also voted in favour.
While the DUP is not in a position to block it, its opposition suggests that an early return to power-sharing at Stormont is highly unlikely.
The executive and assembly have been suspended since the DUP walked out last year in protest at the way the protocol was operating, saying it weakened Northern Ireland's position in the UK.
Downing Street has indicated that there could be further votes in the weeks ahead on the statutory instruments needed to implement other elements of the framework.
However, there is frustration among some MPs that Mr Sunak is resisting calls for an overall vote on the whole framework document.
Foreign Secretary James Cleverly is due to meet the EU's Maroš Šefčovič in London on Friday to formally adopt the pact at a meeting of the joint committee on the Withdrawal Agreement.
Additional reporting: AFP, PA
