David Cameron will leave Downing Street for the final time as PM later, with Theresa May waiting to replace him.
Mr Cameron is taking part in his final Prime Minister’s Questions, before heading to Buckingham Palace to tender his resignation to the Queen.
He told the Daily Telegraph: “As I leave today, I hope that people will see a stronger country. It has been a privilege to serve the country I love.”
After taking office, Mrs May will set about naming her own frontbench team.
The current home secretary, 59, was the only remaining candidate in the Conservative leadership contest following Andrea Leadsom’s withdrawal on Monday.
The contest began when Mr Cameron, who has been prime minister since 2010, announced he would step down after losing the EU referendum in June.
Mr Cameron told the Telegraph: “I came into Downing Street to confront our problems as a country and lead people through difficult decisions so that together we could reach better times.
“As I leave today, I hope that people will see a stronger country, a thriving economy, and more chances to get on in life.”
At midday Mr Cameron, who has said he plans to continue as MP for Witney in Oxfordshire, will face Prime Minister’s Questions for the 182nd and final time as PM – his 319th in total as Tory leader.
Later, after saying goodbye to staff at Downing Street, the PM will tender his resignation to the Queen.
Soon after, Mrs May will then make her own way to Buckingham Palace, accompanied by her husband Philip, when she will be asked to accept the monarch’s offer to form a new government.
Queen Elizabeth is likely to ask the new PM, who will be the 13th leader of her reign, about her “intentions and programme” for government.
Mrs May will then return to No 10 as the country’s second female prime minister, following in the footsteps of Margaret Thatcher.
She is expected to briefly address the nation before meeting top officials, including Cabinet Secretary Sir Jeremy Heyward, and receiving a full national security and defence briefing.
She will be asked to hand-write letters to the commanders of the UK’s four Trident submarines about what to do in the event of a catastrophic nuclear attack on the UK and to appoint two nuclear “deputies” – ministers who will take decisions on the deterrent if she has been rendered incapable.
She is also expected to take calls from a number of foreign leaders. Later on Wednesday, she will get down to the work of putting together her government – with key appointments set to be announced within hours.
Removal vans were spotted outside Downing Street on Tuesday, as Mr Cameron’s ministers paid tribute to him in his final cabinet meeting.
The swift transition of power comes after the expected nine-week leadership campaign was truncated to just a couple of days by leading Brexit campaigner Andrea Leadsom’s surprise withdrawal.
Mrs May, who backed a vote to remain in the EU, will unveil her full ministerial team over the next couple of days, with the focus on the key positions of chancellor and foreign secretary as well who will be put in charge of leading the Brexit negotiations.
She is expected to promote a number of women to senior positions, with International Development Secretary Justine Greening and Energy Secretary Amber Rudd among those likely to get upward moves.