The film studios and former factory will be transformed into a hospital setting that will provide 850 beds in total.
Working collaboratively with Swansea Council, Kier will build a new structure to house the new field hospital inside the existing 11,000 sq m single-tier building.
The firm will also improve existing infrastructure within the studio, including heating, electricity and water supplies, so that it will effectively support NHS teams when the space becomes operational.
Kier is now on site and working with its dedicated and local supply chain, as well as local contractor TRJ, to deliver the field hospital within the month.
Initially, it will provide 500 beds, with an additional 350 beds following in subsequent weeks.
Anthony Irving, managing director for Kier Regional Building Western & Wales, said: “I am immensely proud of our teams who are working tirelessly to deliver the field hospital at Bay Studios in Swansea.
“Working alongside Swansea Council and with our local supply chain, this is a collaborative effort at a time when our communities need it most.”
Meanwhile contractor Andrew Scott is advancing well on work to transform Llandarcy Academy of Sport in Neath into another field hospital.
The firm will be providing new flooring in the covered area and building cubicles for the beds, along with installing the necessary services.
Work is expected to be completed on the 340-hospital bed facility within three to four weeks.