Prime Minister Theresa May has signed off the Swansea Bay City Region deal, insisting she wants Wales “at the forefront of science and innovation”.
The plan is expected to create more than 9,000 jobs and trigger almost £1.3bn of investment in south west Wales.
Mrs May said the deal would “benefit the whole of Wales”.
It comes as First Minister Carwyn Jones told the Guardian Mrs May had a “tin ear” on issues of devolution.
Downing Street said Mrs May’s visits to the four UK nations, which began in Wales, would ensure the government was “engaging and listening to people from right across the nation” as it prepared to leave the European Union.
Mrs May and Mr Jones joined the leaders of four councils in south west Wales to sign the deal at the Liberty Stadium in Swansea on Monday.
Speaking at the ceremony, the prime minister said last June’s Brexit referendum vote was not just about the EU, saying voters wanted “a change in the way the country works”.
“It is part of our plan for Britain,” she said.
“It’s important for this part of Wales. It will be about ensuring that prosperity, growth, that opportunity is available to everyone.”
Mr Jones added: “I’m a strong believer that we are at our best when governments co-operate. Today is a good example of that.”
As well as meeting the first minister, Mrs May saw representatives from a range of sectors and businesses at the signing ceremony.
Projects in Swansea, Carmarthenshire, Neath Port Talbot and Pembrokeshire
- Connecting renewable and conventional energy firms digitally and developing new systems and storage processes
- A “cloud” enterprise zone to attract data companies
- Using the internet to improve health diagnostics, manage data and create personal treatment plans and tele-care
- A steel science centre
Rob Stewart, leader of Swansea council and the city region, said: “This is among the biggest investments Wales has ever seen, so it’s a historic day for the Swansea Bay City Region.”
Speaking ahead of the signing, Mr Jones said: “We have pushed long and hard for this city deal to be signed and have given it our strongest possible backing with £125m of Welsh Government investment.
“This is a package which will deliver jobs and economic growth for all of south west Wales, with clear benefits for all the areas involved.
“Today’s announcement is a transformative deal that will drive the regional economy in a new direction, supported by high-quality jobs and a digital infrastructure.”
Theresa May signs £1.3bn Swansea Bay City deal}