Developed by Swansea Council, initial building work for two basement floors of the 71/72 Kingsway scheme has been completed, paving the way for construction of three more storeys at street level and above.
Bouygues UK are main contractors for the project, which is taking shape at the site where a number of nightclubs were once located. These included Top Rank, Ritzy's, Time and Envy, and, most recently, Oceana.
With construction due for completion by the end of 2023, the development will provide space for 600 jobs in sectors like tech, digital and the creative industries.
Once complete, the scheme will be carbon zero in operation and worth £32.6m a year to Swansea's economy.
It will include 114,000 square feet of commercial floor space featuring flexible co-working and networking opportunities. A new link between Oxford Street and The Kingsway will also be constructed.
Cllr Rob Stewart, Swansea Council Leader, said: "This is a another milestone for the construction of the new development at 71/72 Kingsway, which means progress in future will soon be even more visible to motorists, cyclists and pedestrians who pass the site every day.
"We know from our discussions with local tech and digital companies and entrepreneurs that there's a need for this kind of flexible, modern office space in Swansea.
"This development will meet that demand, help stop businesses of this kind from relocating to other cities and create more footfall and spending for other city centre businesses."
Cllr Robert Francis-Davies, Swansea Council's Cabinet Member for Investment, Regeneration and Tourism, said: "The scheme follows-on from a major transformation of The Kingsway to create a more business-friendly environment as Swansea's £1bn regeneration programme continues.
"Other features of the new development will include a green roof terrace and south-facing balconies overlooking the city centre and Swansea Bay."
The 71/72 Kingsway development is being part-funded by the £1.3 billion Swansea Bay City Deal and supported by the European Regional Development Fund through the Welsh Government.
Construction is also ongoing nearby on a 'living building' project led by Hacer Developments that will be among the UK's first schemes of its kind. Made up of the former Woolworths unit and a new adjoining 13-storey structure, the scheme will include green walls and green roofs, an educational facility, retail, offices, a landscaped courtyard, rooftop solar panels, battery storage and gardens. Pobl Group will manage 50 affordable apartments forming part of the scheme.