Up to 150 people will be employed on the restoration of St Mel's Cathedral in Longford, which was destroyed by fire at Christmas in 2009.
Contract documents for a €30m restoration project were signed this morning with an Irish Consortium made up of building companies from Galway and Longford.
Kevin Faye, from construction firm GEM Purcell, said that the restoration would involve extensive design and require meticulous restoration skills.
The jobs will be created through direct labour and sub-contracts.
Bishop of Ardagh and Clonmacnois Colm O'Reilly said the signing of the contracts marked the most crucial day since the fire.
He said the project will also include a new building training project for trainee stonemasons.
Seamus Butler, chairman of the restoration committee, said the project would be the most significant restoration project in Western Europe this year.