Video report by ITV News Europe Editor James Mates
After a six-week long Conservative leadership contest, Boris Johnson has emerged as the Prime Minister-elect of the UK.
Securing a landslide victory against his opponent Jeremy Hunt, Mr Johnson proclaimed: "We are going to energise the country, we are going to get Brexit done on October 31st."
His contemporaries from across the globe have offered their congratulations, from the US President Donald Trump, to Iranian Foreign Minister Javad Zarif, who sent a stern warning to his former counterpart amid rising tensions between the two countries.
How has the EU reacted?
Alongside French President Emmanuel Macron, incoming EU president Ursula von der Leyen sent her congratulations to Mr Johnson, and acknowledged the "challenging times ahead" for the EU and UK.
"Congratulations to Boris Johnson to be nominated as Prime Minister. I'm looking forward to having a good working relationship with him," she said at a press conference at Elysee Palace.
"There are many different difficult issues to tackle together. We have challenging times ahead of us.
"I think it's very important to build up a strong and good working relation because we have duty to deliver something which is good for people in Europe and in the United Kingdom."
Chief EU negotiator for Brexit Michel Barnier tweeted he was looking forward to "working constructively" with Mr Johnson to "achieve an orderly Brexit".
He also added the EU was "ready also to rework the agreed Declaration on a new partnership in line with #EUCO guidelines".
Outgoing EU President Jean-Claude Juncker tweeted a statement in response to the news, stating: "@BorisJohnson, please accept my warmest congratulations on your appointment as Prime Minister of the United Kingdom.
"I look forward to working together in the best possible way."
What about the rest of the world?
US President Donald Trump - a fan of Mr Johnson's - tweeted his congratulations to the former London Mayor, exclaiming: "He will be great!"
Later at a rally, he rejoiced in the fact that "they call him Britain Trump."
"A really good man is going to be the PM of the UK now. Boris Johnson. He’s good and he’s tough..," he said.
"They call him Britain Trump... People are saying that's a good thing. They like me over there. That's what they wanted. It's what they need.
"He'll get it done. Boris is good."
Video report by ITV News National Editor Allegra Stratton
Iranian Foreign Minister Javad Zarif also congratulated Mr Johnson, however this was shrouded by a grave warning regarding the Strait of Hormuz.
"I congratulate my former counterpart, @BorisJohnson on becoming UK PM," he said.
"Iran does not seek confrontation. But we have 1500 miles of Persian Gulf coastline.These are our waters & we will protect them."
This comes as the relationship between Iran and the West hit tumultuous times, with tensions reaching boiling point when the Iranian Revolutionary Guard seized a British-flagged oil tanker on Friday.
The Prime Minister of Israel Benjamin Netanyahu offered a "heartfelt congratulations from Jerusalem".
"Looking forward to working closely together, both in facing our common challenges and seizing the opportunities ahead," he stated.
The Australian Prime Minister Scott Morrison has stated Mr Johnson "has a reputation for getting things done and making things happen".
"We have a great relationship with the UK and it will remain so with Boris."