Rachel Reeves used her speech at a Welsh business conference to warn against isolationist politics.
Speaking at the Wales Investment Summit, the Chancellor called on attendees to reject the politics of “national retreat”.
The event is the most significant hosted by Wales since the 2014 Nato summit – with more than 300 senior business leaders attending from 31 countries.
The Chancellor told the audience: “I believe in that proud and prosperous future for Wales, and I believe that together we can achieve it, if we reject the isolationist politics of national retreat in whatever guise it comes.
“Whether it seeks to cut off Wales from the rest of Britain, or to cut Britain off from the rest of the world.
“If we choose, instead, the high road of national renewal, we can see the future that is waiting to be built right here.
“This Government is choosing investment, choosing to move forwards, choosing to back business and make working people better off.”
In a recent Welsh Parliament by-election in Caerphilly, Labour lost one of its strongholds to Plaid Cymru, a Welsh pro-independence party, and fell into third place behind Nigel Farage’s Reform UK.
Speaking after the vote, Sir Keir Starmer said he was “deeply disappointed” by Labour’s loss in the constituency and conceded his party “clearly need to do much more”.
In her speech, the Chancellor added: “This is a country rich in tradition, in music, in literature, and the breathtaking landscapes and its proud industrial heritage, a nation which once powered Britain and much of the world through its coal industry.
“That legacy is present wherever you go.
“Earlier this year, at the spending review, I was pleased to be able to provide funding to keep the coal tips safe here in Wales – our bigger task is to make sure that that heritage remains a source of pride and never a retreat or a distraction from the future.
“To make sure that those towns and cities which once powered the last industrial revolution can play a central role in our next one.”
