The Ritz-Carlton is to create 300 jobs when it opens the group's first hotel in Powerscourt, Co Wicklow, next year.
The €120 million investment, in conjunction with Treasury Holdings, will generate up to €60 million a year for the Irish tourism industry, the companies have said.
Some 300 people will be directly employed at the 203 room hotel, with another 500 jobs created during the the two-year construction.