The Council of Europe Development Bank (CEB) has agreed to part fund development of a 1.62 hectare site in Limerick city.
The €85 million from the CEB comes in addition to a commitment from the European Investment Bank (EIB) to provide €85 million for the Limerick opera site.
When completed, the €200 million project will deliver commercial and cultural space in the heart of the city and will be capable of employing up to 3,000 people.
Following the commitment of €170 million in funding, the development is expected to proceed after a public consultation in Spring.
"Today ensures we now have the funding in place that will kick-start a whole new era of economic development in Limerick. This is the single most important development for Limerick as it will raise the entire economic and social standing of the city, with significant knock-on benefits for the region also," said Stephen Keary, mayor of Limerick.
Dr Rolf Wenzel, governor of the CEB, said the opera site in Limerick "ticked every box" for the organisation which is keen to partner on projects that will deliver "transformational benefits for cities". "Given the numbers that will work there, it will be a catalyst for economic growth across Limerick, lifting all areas of the city, particularly those with higher levels of unemployment," he added.
A special purpose vehicle tasked with planning and developing key strategic sites in Limerick city and county, Limerick Twenty Thirty, will act as the developers on the project.
This site will be the largest single project of the programme launched in 2016 which will deliver €500 million worth of “transformational infrastructure” across key sites.