250 additional jobs are to be created by Edwards Lifesciences in Limerick over the next four years.
The expansion will increase to 850 the numbers who will eventually be employed at the Castletroy facility.
In 2018, the company announced it planned to invest €80m in the new plant and create 600 jobs in the process.
A year later it revealed that it was going to double that investment to €160m and now it says the factory will end up employing a further 250 staff.
The plant, which will make new therapies and technologies for patients suffering from heart valve disease, is being officially opened today.
Edwards Lifesciences has also had operations at a facility in the Shannon Freezone for the past three years and across the region the company now employs 250 people.
"Our announcement illustrates the continued growth of our company globally and demonstrates our confidence to the Mid-West of Ireland," said Michael A Mussallem, Chairman and Chief Executive of Edwards Lifesciences.
"By expanding our presence in the area, we aim to create a hub for Europe and bring us closer to the patients in the region who will receive these life-saving therapies."
The news has been welcomed by Tánaiste and Minister for Enterprise, Trade and Employment, Leo Varadkar, who will open the facility.
"It's an enormous vote of confidence in the Mid-West region and the talent, skills and experience on offer here," he said.
Martin Shanahan, CEO of IDA Ireland, which has supported the investment, said it demonstrates the company's commitment to the region.
The Tánaiste will also visit the Bernal Institute in the University of Limerick, where he will launch the second phase of a Government-funded research programme at the Dairy Processing Technology Centre (DPTC).
The next phase will see €14m invested through Enterprise Ireland into sustainability and competitiveness in the dairy sector.
"The establishment of the Dairy Processing Technology Centre anticipated the significant market disruption that would occur with the removal of milk quotas in 2015," said Enterprise Ireland CEO Leo Clancy.
"Anticipating disruption is now an essential part of business planning, and the DPTC was ahead of its time.
"Since then, it has proved how effective collaboration between industry leaders and our research community can be and I am delighted that Enterprise Ireland will provide €14m to back its next phase of research."
Also in the midwest today, Mr Varadkar was launching Ennis 2040, an economic and spatial strategy that aims to create 5,000 new jobs and grow the population of the town by 1.6% per year until 2040.