Prime Minister Rishi Sunak takes the reins with promise to fix Liz Truss's mistakes

Mr Sunak appointed at Buckingham Palace by King Charles III

Britain's new Prime Minister Rishi Sunak delivers a speech outside Number 10 Downing Street. Reuters

King Charles III invites Mr Sunak to become prime minister and form a new government in an audience at Buckingham Palace. PA

Mr Sunak promised to bring stability amid what he called a “profound economic crisis”. PA

The new prime minister is applauded as he enters Number 10. Photo: Simon Walker/ No 10 Downing Street

Mr Sunak is greeted by Cabinet Secretary and Head of the Civil Service Simon Case as he enters 10 Downing Street. AFP

A worker loads a removal van with boxes outside 10 Downing Street. Reuters

Members of the public wait for the arrival of Mr Sunak near Downing Street. AP

Staff in the Foreign and Commonwealth Office watch from the windows as Mr Sunak arrives in Downing Street. PA

An Indian artist in Mumbai creates a painting to congratulate Mr Sunak on becoming prime minister. EPA

Mr Sunak arrives at Buckingham Palace. PA

Incoming prime minister Rishi Sunak arrives at the Conservative Party's headquarters with a wave. AFP

Rishi Sunak is greeted by colleagues upon his arrival. AFP

Conservative MPs applaud as Rishi Sunak arrives. Reuters

Rishi Sunak departs after making a statement inside the Conservative Party's headquarters. PA

Mr Sunak meets the 1922 Committee in Parliament after he was announced as the new leader of the Conservative Party when Penny Mordaunt dropped out. PA

Sir Graham Brady, chairman of the 1922 Committee, announces Mr Sunak as the new leader of the Conservatives and therefore the prime minister. PA

Members of the media work outside No 10 Downing Street, the official residence of Britain's prime minister, in central London, as they await announcements. AFP

Mr Sunak leaves his campaign office in London. AP

A billboard of Liz Truss, the departing prime minister, in London. Bloomberg

Members of the public look through the gates into Downing Street. Reuters

Mr Sunak leaves his home in London on Monday morning. AFP

Leader of the House of Commons and Conservative leadership candidate Penny Mordaunt speaks to the media on Sunday. Ms Mordaunt pulled out of the race moments before the deadline for nominations. PA

Rishi Sunak assumed power as the UK's new Prime Minister on Tuesday, promising to fix the mistakes of Liz Truss's ill-fated tenure.

Mr Sunak, 42, arrived in Downing Street after his appointment by King Charles III, who oversaw the handover of power for the first time.

Speaking for the first time as Prime Minister, he promised to bring stability amid what he called a “profound economic crisis”. The pound climbed as markets welcomed his appointment.

He succeeds Ms Truss just 49 days after she took power, after a misjudged package of tax cuts fatally damaged her authority.

Ms Truss “was not wrong to want to improve growth in this country. It is a noble aim and I admired her restlessness to create change. But some mistakes were made,” Mr Sunak said.

“And I have been elected as leader of my party and your prime minister in part to fix them. That work begins today.”

Mr Sunak promised to restore trust as he drew a line under the premierships of Ms Truss and Boris Johnson, who called off an audacious comeback attempt on Sunday.

In a six-minute speech, in which he was not flanked by family or supporters, he said difficult decisions lay ahead as ministers seek to reassure markets.

Jeremy Hunt, the Chancellor of the Exchequer brought in to stabilise the economy, was quickly re-appointed by Mr Sunak.

As he began forming his cabinet, ministers close to Ms Truss including Simon Clarke and Jacob Rees-Mogg announced they were leaving the government.

“I fully appreciate how hard things are. I understand too that I have work to do to restore trust after all that has happened,” Mr Sunak said.

“All I can say is that I am not daunted. I know the high office I have accepted and I hope to live up to its demands.”

Mr Sunak was invited to form a government at Buckingham Palace after winning the Conservative Party leadership on Monday.

He is the youngest prime minister for more than 200 years, the first Hindu and the first of Asian heritage.

As Britain's third leader in two months, he faces an array of challenges including economic strife, high inflation, the war in Ukraine and a fractured ruling party.

Ukrainian President Volodymyr Zelenskyy was among the first world leaders to send his congratulations, after US President Joe Biden called it a "groundbreaking milestone".

French President Emmmanuel Macron said France and Britain would "continue working to tackle the challenges of the moment", including the war in Ukraine.

While opposition parties call for an election, Mr Sunak signalled an early vote was not on the cards by saying he would return to the pledges of the Tory manifesto in 2019.

In a nod to Mr Johnson's victory that year, he said: "I know he would agree that the mandate my party earned in 2019 is not the sole property of any one individual."

Rishi Sunak through the years - in pictures

British Prime Minister Rishi Sunak announces July 4 as the date for the 2024 general election at No 10 Downing Street. Here, The National looks back at his political career. Getty Images

Mr Sunak during local election campaigning in Teesside in May 2024. Getty Images

Mr Sunak presents cupcakes to journalists on board a plane on the way to Warsaw in April 2024. Getty Images

Mr Sunak during a press conference in Downing Street in January after the Safety of Rwanda Bill passed its third reading in the House of Commons. Getty Images

Being applauded after his speech at the Conservative Party conference in October 2023. Getty Images

Looking pensive alongside then-home secretary Suella Braverman at No 10 in October 2023. She didn't last much longer in the cabinet. Getty Images

Mr Sunak sits in an old Special Branch police vehicle which was used to transport former prime minister Margaret Thatcher, in July 2023. Getty Images

On board Border Agency cutter HMC Seeker during a visit to Dover in June 2023. Getty Images

Mr Sunak alongside European Commission President Ursula von der Leyen, Canada's Prime Minister Justin Trudeau, US President Joe Biden, French President Emmanuel Macron and German Chancellor Olaf Scholz during the G7 Summit in May 2023. Getty Images

Mr Sunak and his wife Akshata Murty arriving in Japan ahead of the G7 Summit in May 2023. Getty Images

Mr Sunak and Chancellor Jeremy Hunt sending a message at Accrington Market Hall in January 2023. Getty Images

Mr Sunak and Ukrainian President Volodymyr Zelenskyy meet in Ukraine's capital Kyiv in November 2022. Getty Images

King Charles III welcomes Mr Sunak during an audience at Buckingham Palace, where he invited the newly elected leader of the Conservative Party to become Prime Minister and form a new government in October 2022. Getty Images

Mr Sunak makes a statement outside No 10 in October 2022 after taking office. Getty Images

Mr Sunak arrives inside Number 10 in October 2022. Photo: Simon Walker/ No 10 Downing Street

Greeted by colleagues at Conservative Party HQ after having been announced winner of the leadership contest in October 2022. Getty Images

Mr Sunak at Westminster Hall in London following the death of Queen Elizabeth II in September 2022. PA

Mr Sunak visits his family's old business, Bassett Pharmacy, on the campaign trail in August 2022. Getty Images

Mr Sunak looks at an NLAW anti-tank launcher during a visit to the Thales Defence System plant in Belfast in August 2022. Getty Images

At a hustings event in Exeter in August 2022. Getty Images

Celebrates England's first goal as he watches the Women's Euro 2022 final in Salisbury in July 2022. Getty Images

Mr Sunak and Ms Truss take part in the BBC Leadership debate at Victoria Hall, Hanley, in July 2022. Getty Images

With daughters Krisna and Anoushka and wife Akshata Murthy in July 2022. Getty Images

Opening the Great Ayton Village Fete during the queen’s Platinum Jubilee celebrations in June 2022. Getty Images

Mr Sunak and Ms Murthy speak to then-Prince Charles at a British Asian Trust event in February 2022. Getty Images

Mr Sunak arrives at COP26 in Glasgow in November 2021 when he was chancellor. Getty Images

Holding the budget box as he departs 11 Downing Street to deliver his Autumn Budget in October 2021. Getty Images

At a press conference on the 2021 Budget in London in March 2021. Getty Images

With former prime minister Boris Johnson during a visit to PD Ports on the River Tees in March 2021. Getty Images

Mr Sunak poses with the budget box at 11 Downing Street in March 2021. Getty Images

Meeting staff back at work after being furloughed at Hamleys toy shop in London, December 2020. Photo: HM Treasury

Mr Sunak visits the Imperial Clinic Research Facility at Hammersmith Hospital, London, in November 2020. Getty Images

Lighting a candle for Diwali on Downing Street, November 2020. Getty Images

Working on a speech in his flat above 11 Downing Street in November 2020. Photo: HM Treasury

Mr Johnson and Mr Sunak visit the headquarters of Octopus Energy in London in October 2020. Getty Images

With his 'Winter Economy Plan' outside 11 Downing Street in September 2020. AFP

Decorating a plate at Emma Bridgewater pottery in Stoke pottery in September 2020. Getty Images

Promoting 'eat out to help out' on the Isle of Bute, Scotland, in August 2020. Getty Images

A member of the public takes a selfie with Rishi Sunak during a visit to Scotland in August 2020. AFP

Visiting a Wagamama restaurant in central London in July 2020. Photo: HM Treasury

Rishi Sunak visits a Pret A Manger in Westminster in July 2020. HM Treasury

With Mr Johnson at his first Cabinet meeting after a reshuffle at 10 Downing Street in February 2020. Getty Images

Mr Sunak speaks during a general election debate in Cardiff in November 2019. Getty Images

Mr Johnson's resignation in July was precipitated by a cabinet mutiny when Mr Sunak, the former chancellor of the exchequer, joined dozens of ministers in walking out.

But he called Mr Sunak's appointment a "historic day" and said it was a moment for the Conservatives to unite.

The president of a Hindu temple in Southampton set up by Mr Sunak's grandfather said the appointment of Mr Sunak was "our Barack Obama moment".

"It will unite the country, because he practises Hindu religion religiously and one of the key values we have is the whole world is our family and we believe in unity in that respect," Sanjay Chandarana told PA.

As part of the choreography of the handover, Mr Sunak spoke outside 10 Downing Street's black door and at a different lectern to the one used by Ms Truss.

Ms Truss earlier departed Downing Street with her husband and two daughters only 49 days after she took office.

In a defiant farewell speech, she defended the pro-growth policies that led to her demise but said that “brighter days lie ahead”.

Tory MPs turned on Ms Truss after her package of more than £40 billion ($45.2bn) in tax cuts caused mayhem in financial markets.

But she said: “We simply cannot afford to be a low-growth country where the government takes up an increasing share of our national wealth."

She said she was honoured to have overseen the mourning period for Queen Elizabeth II, who appointed Ms Truss her final prime minister two days before she died.

Liz Truss's final day as prime minister - in pictures

Departing British Prime Minister Liz Truss speaks outside Downing Street, as her premiership ends after just seven weeks. AP

King Charles III arrives at Buckingham Palace to meet Ms Truss. Getty

Ms Truss arrives at Buckingham Palace to formally resign. PA

Ms Truss's daughters Frances and Liberty are greeted by King Charles's equerry Lt Col Johnny Thompson at Buckingham Palace. PA

Liz Truss is applauded as she walks out of Number 10 for the last time as prime minister. Photo: No 10 Downing Street

Liz Truss's husband and daughters watch on as she speaks. Getty

Journalists pack into Downing Street as Ms Truss makes her statement. PA

Mr Truss, with her husband Hugh O'Leary and their daughters, leaves Downing Street. PA

Ms Truss walks out of Number 10. Reuters

Staff place a podium in front of Number 10 Downing Street before Ms Truss delivers a speech. Reuters

Deputy Prime Minister Therese Coffey takes a selfie while waiting for Mr Truss to make a speech outside 10 Downing Street. PA