Tesco has opened three new supermarkets and created 310 new jobs.
The stores have been opened in Oranmore in Galway, Swinford in Mayo and Ballybeg in Waterford.
The Chamber of Commerce in Swinford has said the jobs are extremely important for the town at a time when many young people are being force to emigrate and when attracting multinational firms is becoming increasingly difficult.
The stores in Oranamore and Ballybeg will both employ 110 people, while 90 jobs have been created in Swinford.
Another 15 jobs are expected to be created when a Tesco Express Store opens in Newcastle in Galway city next week.
Tesco Ireland Chief Executive Tony Keohane said: 'We are once again very pleased to highlight Tesco's commitment to Ireland with the opening of these three new stores.'
He said all of the jobs were permanent and will give a significant boost to local employment in all three counties.
Mr Keohane also said the retail sector had a very important role to play in stimulating the economy at this time.
Today's openings are part of Tesco Ireland's €113m national investment plans for 2010/2011.
Commenting on the expansion, Jackie Cahill of the Irish Creamery Milk Suppliers Association (ICMSA) said that no Irish food producer would be cheered by the news.
He said it was obvious that the jobs being created would be at the expense of existing smaller and independent local retail outlets.