The Prime Minister last night led the political tributes to Arlene Foster after she announced she was stepping down as DUP leader and First Minister.
Boris Johnson described Mrs Foster as a committed politician.
"I want to thank Arlene Foster for her dedication to the people of Northern Ireland over many years," he tweeted.
"She will continue to play a vital role as First Minister until June and I hope that she stays in public service for years to come."
Mrs Foster will stand down as party leader on May 28 and as First Minister at the end of June after bowing to a major internal heave against her.
Reflecting on her nearly six-year tenure, Mrs Foster said serving the people of Northern Ireland was the privilege of her life when she announced her resignation yesterday.
Her decision comes after DUP colleagues disgruntled with her leadership moved against her, with a majority of senior elected representatives signing a letter of no confidence.
Central to the resignation was the discontent at the DUP's Brexit strategy, with the party rank-and-file laying some of the blame for the Irish Sea border at her door.
Traditionalists from the party's religious fundamentalist wing also harboured concerns over positions Mrs Foster had taken on some social issues.
Messages of well-wishes also came from wider unionism, with Ulster Unionist leader Steve Aiken saying that he wished Mrs Foster "all the best for the future"
"Politics is a difficult arena which can take an enormous toll, on both you personally and your family," he added.
TUV leader Jim Allister, who has been a vocal and ardent critic of the contentious Northern Ireland Protocol, last night called for Mrs Foster's successor to unpick the trade border between Great Britain and Northern Ireland.
"I have no doubt this has been a very difficult day for Arlene Foster and that the speed of her dispatch will have added to the hurt," he reflected.
"I therefore wish Mrs Foster and her family all the best for the future."
Mr Allister said he had known Mrs Foster for many years dating back to when they both practised law.
"In all my dealings with her I found her straightforward and honourable, whatever our political differences," he said.
"Going forward, I trust the new DUP leader will be wholly committed to restoring the Union and undoing the severe damage done by the iniquitous protocol.
"Only the unstitching of the Union-dismantling protocol can restore our place within the United Kingdom and afford us the equal citizenship we require. This should be the priority of every unionist."
Alliance Party deputy leader Stephen Farry described Mrs Foster as "heavily committed to public service".
The North Down MP tweeted: "I wish Arlene Foster well. I have known Arlene for 30 years, and have worked with her on achieving record levels of inward investment to NI.
"She has been heavily committed to public service. There will be other chances to talk of her legacy as DUP leader and what happens next."
Taoiseach Micheal Martin hailed Mrs Foster for breaking ground for women in politics as the first female Stormont leader. He said Mrs Foster had worked hard over many years and that he "valued the constructive engagement, notwithstanding our differences".
"She has worked hard over many years as an elected representative for the constituency of Fermanagh/South Tyrone.
"I know especially how proud Arlene is of her homeplace of Co Fermanagh. Political leadership is often not easy and takes courage."
Mr Martin described the re-establishment of the Stormont Executive in January 2020, with Mrs Foster as First Minister and Michelle O'Neill as Deputy First Minister, as a "key development in supporting peace and stability for all the people of these islands". The Irish President also praised Mrs Foster for her public service over the years.
In a statement, Michael D Higgins said: "Serving in public life makes great demands on individuals, which is important to acknowledge.
"May I wish her health and happiness in the future."