The Wiltshire-based company said it had responded to the government's call for assistance to combat the disease coronavirus pandemic in the UK.
Founded by billionaire inventor Sir James Dyson, the company has worked around the clock to develop a ventilator for hospital patients.
ITV News reported that the work included using vacuum cleaner components and testing prototypes on pig lungs.
A Dyson spokesman said, "Dyson responded with his Covid-19 response to the government's request for support by focusing resources on the design and manufacture of a fan for the NHS.
"This is a very complex project that is being carried out in a very challenging time frame.
"We have deployed expertise in air displacement, engines, energy systems, manufacturing and supply chain and partner with medical technology and development company TTP, The Technology Partnership, based in Cambridge.
"We worked together around the clock and the past two weekends to develop a meaningful and timely response.
"We are conducting fully regulated medical device development, including laboratory and human testing, and scale up by volume."