Four private healthcare facilities ultimately owned by businessman Larry Goodman are to be brought together under the one group structure.
Blackrock Health will include the Blackrock, Galway, Hermitage and Limerick Clinics.
However, each of the hospitals will continue to trade with its existing name.
"Blackrock Health has a very supportive shareholder, who has been a consistent investor for 19 years," said chairperson of the new group, Bryan Harty.
"We have a strong balance sheet which means we will be able to invest in innovation and technology, infrastructure and in our people."
"This is an exciting and challenging time for healthcare in Ireland and Blackrock Health intends to play a leading role in ensuring patients have access to world class clinical care."
The group is to be led by chief executive, Dr Caroline Whelan, and will include 2,800 staff and 600 consultant surgeons and physicians.
Collectively, the hospitals have 450 inpatient beds and 24 operating theatres and treated 25,000 in-patients and 200,000 outpatients last year.
Further expansion is planned with an initial focus on acute cardiology and orthopaedic services.
Ownership of some of the assets in the group was the subject of a number of High Court actions in recent years involving Mr Goodman's companies and other shareholders.
