UP to 850 jobs are earmarked for the aviation sector when Shannon airport becomes an independent facility at the end of the year.
The Government has revealed that on December 31 Shannon will separate from Dublin Airport Authority (DAA), leaving the authority saddled with €100m worth of debt.
The airport will be merged with a restructured Shannon Development to form a new, publicly-owned, commercial entity in 2013.
Transport Minister Leo Varadkar and Enterprise Minister Richard Bruton said 850 jobs have been secured from two local companies as part of the plan for an international aviation services centre (IASC).
Mr Varadkar said the decision was historic and will free the board and management of Shannon airport, together with their employees, to bring a fresh approach to the future development of the airport.
"A key element of that future will be the development of an international aviation services centre in and around the airport, building on a range of aviation-related activities already undertaken in Shannon such as aircraft maintenance and leasing," he added.
About 220 people are employed at Shannon, which has been loss-making since 2008, with passenger numbers down 60% over the past five years.
The Siptu trade union said it is disappointed by the move, which it described as fanciful and unrealistic given that it is based on a model which envisages an increase of passenger numbers by 50% within a short timescale.
Siptu organiser Tony Carroll said: "Staff have genuine concerns around their job security and quality of employment and other related matters.
"The speed with which the implementation of this decision is happening does not leave a lot of time for the necessary guarantees to be received."
Ryanair boss Michael O'Leary criticised the move and maintained Shannon airport should be sold to a private owner instead of being transferred to another quango.
Liam Scollan, of Ireland West Airport Knock in Mayo, also revealed he is considering taking a legal challenge in Europe over the Government's decision to separate the airports on a debt-free basis.
He claimed it amounts to illegal State aid and will result in a gross distortion of the market.
The Government decision to separate Shannon from DAA was taken last May but the details were finally revealed at a conference on aviation policy for Ireland in Dublin.
A report by the Shannon Aviation Business Development Task Force projected 3,000 to 3,500 new direct jobs will be created and maintained within five years.
DAA, which retains Aer Rianta International, said it will continue to work with the Government to implement the shareholder's decision in relation to Shannon airport.
Mr Bruton argued the establishment of an independent Shannon airport, along with the restructure of enterprise agencies in the region, would drive the creation of a world-class aviation industry in the region.
"The implementation of these decisions represents a new start for enterprise and jobs in the Shannon region," he added.