The historic Govan shipyard has been reprieved, following a review of Glasgow's two naval yards by owners BAE Systems.
The company said it had decided to invest more than £100m in improving and expanding its Govan and Scotstoun sites.
The move ends fears over the future of the Govan shipyard.
BAE had been considering a second option of a new £200m single-site manufacturing facility at Scotstoun.
This would have meant closing the Govan yard.
Last year the company lodged planning applications for both proposals but indicated that it preferred the single-site option.
The Govan yard is currently being used to build sections of the second of the Royal Navy's new aircraft carriers.
The new investment is to prepare for the Type 26 warship, being designed to replace the Royal Navy's frigates.
A BAE spokesman said: "Following an assessment of potential facilities options, we have decided to retain and invest in both of our sites in Glasgow.
"We will work closely with our trade unions as we prepare the detailed designs to improve and expand our manufacturing facilities, which will mark the most significant investment in the Glasgow shipyards in decades."
He added: "Together with investments in new technologies, cutting-edge processes and new ways of working, improved infrastructure will play a key role in transforming the way we design and build complex warships.
"This will enable us to create a modern, safe and inspiring workplace for our employees, whilst ensuring we deliver equipment to the highest quality at the lowest possible cost so we can compete effectively for future UK and international orders."
The union GMB Scotland, which represents shipbuilding workers, welcomed the news.
Senior organiser Jim Moohan said: "The two yards working together will make Clydeside attractive for potential new customers.
"It will also sustain job security with orders for the Type 26 ships for the Royal Navy coming on stream.
"I am of the view that it will enhance our chances of securing export opportunities that have been elusive."
Deputy First Minister John Swinney also welcomed the move, describing BAE as "a major player in the Scottish and UK defence industry".
He said: "BAE still has ambitions to seek export opportunities as well as progressing with MoD orders and Scottish Enterprise will continue to work closely with the company to offer support."
In a joint statement, Glasgow SNP MPs Chris Stephens and Carol Monaghan said: "This decision by BAE is a testament to the abilities of the highly skilled workforces and it is important that we recognise the world-leading expertise that we have here on the Clyde.
"We look forward to working closely with BAE in the future."
'Statement of confidence'
Scottish Conservative West of Scotland MSP Annabel Goldie described the move as "a tremendous statement of confidence" in the United Kingdom's defence capacity.
She added: "It is also a very welcome statement of confidence by BAE in the skills of shipyard workers in Scotland."
Glasgow City Council leader Gordon Matheson said: "The council's priority is to support BAE Systems in keeping these high quality shipbuilding jobs on the Clyde.
"The investment in the Glasgow yards is testament to the professionalism and commitment of the workforce, and ensures the city will keep on producing the world's most advanced ships."