The government's Northern Powerhouse project is gathering strength and now has "Chinese backing", David Cameron has said.
It comes as the PM and Chinese President Xi Jinping spent the last day of Mr Xi's state visit in Manchester.
Mr Xi visited Manchester University and joined the prime minister at Manchester City's football academy.
He then ended his UK trip at Manchester Airport and announced plans for direct flights between Manchester and Beijing.
By Carrie Gracie, BBC China editor
The broadest smile of the state visit came when the football mad Chinese president met some of his idols at Manchester City. United players were also present and to avoid offence, he wore a red tie at the ground of the Blues.
It was just one example of the choreography which has governed every moment of the visit. And the Chinese side are delighted with their week.
They got the pictures they wanted in gilded carriages and Buckingham palace. They got the deals they wanted to embed their companies in the UK's civil nuclear power and their currency in the City of London. And the human rights protesters were penned behind barriers so that President Xi never had to confront them.
The hosts too were pleased, relieved and hopeful for a golden era in UK-China relations.
But after the banquets, the toasts and the talk of billions, it remains to be seen what the golden era amounts to. And how resilient it will prove when the two governments next disagree.
Mr Xi and Mr Cameron visited Manchester Airport, where the new Hainan Airlines route - which the UK government says will provide a £50m boost to the Manchester economy - was announced by the Chinese president.
It will be the first direct route from outside London in the UK to China and flights are due to begin from June 2016.
Mr Xi and Mr Cameron also announced the £130m "China Cluster" project at Airport City Manchester.
Airport City Manchester is an £800m joint business development between British and Chinese companies.
The China Cluster will provide a commercial base for Chinese businesses arriving in the UK.
Earlier the leaders met current and former Manchester City and Manchester United players, including Gary Neville, Patrick Vieira, Denis Law and Mike Summerbee, at the Manchester City football academy.
The president, who is reportedly a Manchester United fan, was given a tour of City's 80-acre training complex and was shown the last-minute goal that clinched the club the 2012 Premier League title.
Speaking after the visit, Mr Cameron told the BBC: "I think this is a great day for Manchester and a great day for the whole of the north of England.
"You can really see the Northern Powerhouse gathering strength and it's now got Chinese backing too," he added.
Mr Xi had lunch at Manchester Town Hall alongside Mr Cameron and business, civic and community representatives.
In the morning he joined the Chancellor George Osborne for a visit to the National Graphene Institute at the University of Manchester.
The science institute leads research into graphene, a super-strong, flexible and electrically conductive material.
Mr Osborne said billions of pounds of investment would be coming into northern England, saying there was now "unstoppable momentum" behind the Northern Powerhouse project.
A series of investment deals have been signed during Mr Xi's four-day visit to the UK, including an agreement with EDF Energy and China General Nuclear Power Corporation (CGN) for a nuclear power plant at Hinkley Point, Somerset.
On Wednesday, the two leaders held talks at Chequers focusing on "domestic priorities and foreign policy issues".
Downing Street said they had agreed that early dialogue between the two countries could help find diplomatic solutions for global and regional security challenges.
The visit to Manchester came as Mr Osborne announced new devolution deals for the North East of England.
The chancellor's measures will mean Newcastle and Sunderland, and Tees Valley will both vote in a directly-elected mayor in 2017.