Diageo plc - the parent company of Guinness UDV Ireland - is to invest €38 million at its breweries in Waterford and Dundalk.
The bulk of the investment will be made in Waterford where €34 million is to be spent on a new production facility.
Announcing the investment, the Tánaiste, Ms Harney, said it was needed to help meet the increased demand for ingredients that are used in the brewing of Guinness at 50 breweries around the world.
No new jobs are expected to be created but Ms Harney said the investment safeguarded existing jobs.
"There is a long history of brewing in Waterford and this expansion will underpin the long-term viability of this type of industry. I am particularly pleased that this level of investment has been secured for Ireland - the home of Guinness," she said.
