Penlon in Abingdon and Williams in Grove were among the businesses helping to produce over 14,000 of them.
Scientific modelling at the start of the coronavirus crisis predicted that the NHS was going to run out of ventilators.
So the Government launched the Ventilator Challenge with a call to arms to manufacturers and medical device companies to step up production of existing designs and design new ventilators from scratch.
The Government received an overwhelming response, with over 5000 companies offering their support and over 7500 members of staff contributing to the effort.
Yesterday, on the 72nd birthday of the NHS, Abingdon-based Penlon dispatched its final load of newly-adapted ventilators to the NHS.
Penlon is now making more ventilators in one day than the company used to deliver in ten months, further underlining the success of the scaling up of the device.
It has also been confirmed that the Penlon ventilator has had its CE mark confirmed, meaning that the device, which was newly adapted for the Ventilator Challenge, is now available for export abroad.
Penlon is now setting up a new line aimed at exporting across the world.
Prime Minister Boris Johnson said: "The Ventilator Challenge has proven just how much Britain can achieve when confronted with a difficult problem – bringing together the best minds in manufacturing, innovation and design.
"Thanks to these efforts, everyone who needed a ventilator has had access to one, and the NHS has the vital machines it needs to continue providing life-saving support against this deadly virus."
A number of Oxfordshire's F1 teams were also involved in the challenge since March, including Williams in Grove, Haas F1 in Banbury and Renault F1 at Enstone.
Technicians, engineers and scientists from STFC's Rutherford Appleton Laboratory at Harwell also played a big part.
Over 70 of them helped test and calibrate Penlon's ventilators. They monitored pressure and air flow through the device while it inflated and deflated a set of steel "lungs".
Geoff Gilley, a senior engineer in STFC's Technology department, spoke to JACKfm:
Dr Kristian Harder, STFC's Particle Physics Department added: "Our small but effective team of scientists, engineers and technicians volunteered to help with this urgent task and we were able to support, train, and, in some cases, lead parts of the testing and rework effort.
"We've made interesting connections outside the research community that will persist beyond the end of the Ventilator Challenge."
The Government says NHS now has a 'readily available supply of devices that will enable the health service to have resilience of supply for possible future pandemics.'