David Cameron and Boris Johnson have unveiled plans to transform Tech City in east London.
The Old Street roundabout is to be given a £50 million makeover to become a centre for technology start-ups and entrepreneurs.
It will become Europe's largest civic indoor space, hosting classrooms and workshops equipped with the latest 3D printing technology.
Several large international firms have also announced new investments in the area, including Microsoft, IBM and KPMG.
Cameron hailed the success of the capital's technology industry at the Urban Age Electric City Conference in Shoreditch.
The Prime Minister said: "Two years ago I set out my commitment to help Tech City become one of the world's great technology centres.
"Today we are seeing it continue to grow and go from strength to strength - and that is down to the talented, creative entrepreneurs who have set up there.
"The UK is in a global race and I am determined that we as a Government continue doing everything we can to equip the UK to compete and thrive in that race.
"As well as backing the businesses of today, we are creating an aspiration nation and also backing the innovative, high-growth businesses of the future.
"That's why we're investing in creating the largest civic space in Europe - a place for start-up companies and the local community to come together and become the next generation of entrepreneurs."
Software giant Microsoft revealed it is to establish a technology development centre in the heart of Tech City to provide expertise and guidance for people with new and innovative ideas.
KPMG, the professional services company, is to open an office in Shoreditch with a dedicated team to support early stage technology companies, and technology firm IBM is to bring its global entrepreneur programme to the area.
Mayor of London Boris Johnson said: "The time is right to lay solid foundations in Tech City for London's digital revolution, and this list of major new firms committing to the area is a testament to the confidence leading tech entrepreneurs have in the capital.
"Our new centre will provide not only a vital resource to nurture upcoming technology and creative superstars from around the world, it will drive huge investment into the capital and help create thousands of jobs.
Glenn Shoosmith, chief executive of online booking firm Bookingbug, was one of a number of representatives from Tech City-based firms to meet the Prime Minister during a visit to the Central Working business hub in Shoreditch.
He claimed the regeneration of the Old Street roundabout was an important boost.
Shoosmith said: "You've got an area at the moment that is partly loved and partly hated so any change is always going to be controversial.
"But this kind of urban regeneration needs doing. You get to Old Street and you're supposed to see all these tech companies. All you see is a not very nice roundabout and a not particularly great Underground area at Old Street station.
"You look at something like Canary Wharf and you see across London all kinds of fabulous architecture and regeneration of the city. I think Old Street needs that vision as well."
The full list of announcements included:
- Microsoft "establishing a Technology Development Centre in the heart of Tech City"
- Cisco, DC Thomson and UCL are opening IDEALondon, "an innovation centre in Shoreditch to support the growth of digital and media companies"
- KPMG to open an office in Shoreditch, with a dedicated team to support early stage technology companies
- IBM will bring its entrepreneur programme toTech City
- Alert Me is moving to Tech City.
- Barclays and Ravensbourne announce a new creative partnership, that will see Barclays working with - and offering placements to - Ravensbourne students
- Skills Matte announce an5m investment by Beringea
- Salesforce.com working with the Tech City Investment Organisation to support a programme of events that will showcase Tech City start-ups