Liz Truss was appointed as the prime minister of Britain after meeting Queen Elizabeth II at the latter's summer residence of Scotland's Balmoral Castle.
This comes shortly after Boris Johnson formally tendered his resignation to the queen earlier in the day.
The 47-year-old Conservative Party leader is scheduled to be flown back to London to make her inaugural speech from 10 Downing Street.
Truss had defeated the former Chancellor of the Exchequer Rishi Sunak, garnering 81,326 Tory votes, compared to Sunak’s share of 60,399 votes, to clinch the top post. A total turnout of 82.6 percent was recorded in the election.
Following his defeat, the 42-year-old Indian-origin leader had urged everybody in the UK to "unite" behind the new PM.
Truss' Speech on Monday
After being announced the winner by Chair of the 1922 Committee, Sir Graham Brady, Truss promised to tide over the economic crisis plaguing the country.
"I will deliver a bold plan to cut taxes and grow our economy. I will deliver on the energy crisis, dealing with people's energy bills, but also dealing with the long term issues we have on energy supply," she said.
The Tory leader also thanked outgoing PM Johnson, saying that he was "admired from Kyiv to Carlisle."
"Boris, you got Brexit done. You crushed Jeremy Corbyn. You rolled out the vaccine and you stood up to Vladimir Putin. You are admired from Kyiv to Carlisle," Truss asserted.
Before resigning, Johnson said that his policies had given the United Kingdom the economic capacity to help people brave through the ongoing energy crisis.
"I am like one of those booster rockets that has fulfilled its function,'' he said while addressing the press outside 10 Downing Street, adding, "I will now be gently re-entering the atmosphere and splashing down invisibly in some remote and obscure corner of the Pacific.''
This marks the first time the transfer of power is taking place at the Balmoral Castle, instead of the Queen's official residence at London's Buckingham Palace.