“People and places … have been waiting too long for politics to let them hope again … We’re going to give them hope back,” he vowed at a special party conference.
“I am for us, for all of us,” he told cheering delegates.
Burnham takes over from Keir Starmer, who resigned last month as premier after months of political turmoil, scandal and missteps.
Centre-left Labour retains an overwhelming majority in parliament after the 2024 elections, so the leader of the largest party becomes the country’s prime minister, without new polls being held.
It is only four weeks since ex-Manchester mayor Burnham sensationally returned as a member of parliament following a nine-year absence, determined to replace Starmer.
On Monday, he will become the UK’s seventh prime minister in a decade, with Labour MPs betting Burnham is the party’s best chance of reining in Nigel Farage’s anti-immigrant Reform UK party, tipped in the polls to win the next general election, expected in 2029.
Nicknamed “King of the North” for winning three successive elections to the Greater Manchester mayoralty, Burnham’s flagship idea is devolving powers to other cities in a bid to fire up Britain’s economy, including by setting up a “Number 10 North” office.
He said the past four decades since “the 1980s have not been kind to the places that built our party, nor to the communities across the UK in rural and coastal areas. So we pledge today, to them, to be better.”
“If we want an economy and a country that works for all people and places … then it requires a new path to the one we’ve been on for the last 40 years,” he said.
Hailing from the party’s so-called soft left, Burnham favours more public control of services and reindustrialisation.
After facing no challengers, he becomes leader at his third attempt, following failed bids in 2010 and 2015.
Burnham, an MP between 2001 and 2017 and former government minister, has since reinvented himself as a man of the people, melding a relaxed folksy style with slick social media videos.
Labour MPs hope he can communicate with the public better than Starmer and that he is willing to take a more radical approach to reforming Britain’s battered public services.
“Let’s take a problem solving rather than a point scoring approach. Let’s have the courage to fix the big things that politics has neglected,” he told the conference.
