Sir Keir Starmer signalled that more powers could be devolved to London Mayor Sadiq Khan to get the capital fully thriving.
At his first press conference in Downing Street, he stressed that on Tuesday he would hold a meeting with the mayors of cities across Britain to discuss how those who have “skin in the game” can take more decisions and hold more responsibilities.
His “door was open” to Mr Khan and other regional leaders, he added, to work with the new Labour government to boost their areas.
Sir Keir said: “The principle I operate to is those with skin in the game know what is best for their communities and that does require us to be bold about pushing power and resource out of Whitehall.
“Therefore I shall hold a meeting of the metro mayors to discuss with them their part in delivering the growth that we need across the United Kingdom.”
He emphasised that this meeting would include non-Labour metro mayors.
“There is no monopoly on good ideas and I’m not a tribal politician,” he added.
“The principle I operate to whether its mayors or other elected representatives is that where regional leaders want to deliver for their area then regardless of the colour of their rosette, my door is open and my government will work with them.”
He explained that he was looking forward to “constant obstacles not being put in my way” with the Conservatives ousted from Whitehall.
In an interview with The Standard at the start of the election campaign, Sir Keir stressed that a Labour government would end the “bashing” of London and instead get more homes “built at speed” in the capital by working more closely with Mr Khan.
Tory Cabinet ministers of recent administrations clashed repeatedly with the Mayor of London over transport, crime, the environment and other issues.
Some of them also took swipes at the capital as they pursued their levelling-up agenda for other parts of the country.
Sir Keir stressed that the landslide victory in the General Election has given Labour "a clear mandate to govern for all four corners of the United Kingdom".
The Prime Minister, on his first full day in No 10, set out plans to travel on Sunday to Scotland, Northern Ireland, Wales and then back to England.
He said he was "restless for change" but warned that changing the country "is not an overnight exercise".
After sweeping to a historic victory at the polls, Sir Keir said his party had received "a mandate to do politics differently".
He added: "This will be a politics and a Government that is about delivery, is about service. Self-interest is yesterday's politics."
He would chair a series of “delivery boards” as the new Government would be judged on “actions not on words” as it puts economic growth as the No1 priority.
The news conference on Saturday came after he chaired the first meeting of the new Cabinet.
He said he had told his ministers "exactly what I expect of them in terms of standards, delivery, and the trust that the country has put in them".
The Prime Minister said it had been a "moment in history" on Saturday morning as some of his top team received their privy seals, which was followed by a meeting in No10.
Sir Keir stated: "At that meeting, I had the opportunity to set out to my Cabinet precisely what I expect of them in terms of standards, delivery and the trust that the country has put in them.
"And yesterday I met Laurie Magnus, the independent adviser on standards, to discuss how we deliver in Government.
"At the Cabinet meeting I also discussed mission delivery, how we would put into action the plans that we had set out in our manifesto."
Sir Keir labelled the previous government's Rwanda scheme a "gimmick" which was "dead and buried before it started".
He pointed to the appointments of Sir Patrick Vallance as science minister and business chief James Timpson as prisons minister as evidence of his party's commitment to change.
"The thing that's changed already is the mindset of the Government," the Prime Minister said when asked if he could offer one concrete promise to voters about delivery in the first 100 days.
Sir Keir has received a string of phone calls from world leaders to congratulate him on becoming PM and will meet many of them at a Nato summit in Washington on Tuesday.
Labour won 412 seats and the Tories 121, marking the worst result in Conservative history, with Sir Keir’s party having a majority of 174.
After a low turnout at the polls, the new PM stressed the need to rebuild trust in the political system after 14 years of Tory rule marred by the partygate scandal and the chaos of Conservative infighting.
Labour's vote share also suggests the new Government is unlikely to enjoy much of a honeymoon period, with around 34 per cent of the electorate backing the party - less than Jeremy Corbyn secured in 2017.
