The IRFU have confirmed the sale of 92 acres of land in south-west Dublin for €27m.
Irish real estate investment company Hibernia REIT have acquired the land in the Newlands Cross area which the IRFU initially bought in the mid-90s.
IRFU chief executive Philip Browne said the money will be used to help the game flourish at grassroots level.
"The IRFU regards the delivery of a sustainable, long-term additional income stream for investment in the domestic game, for the benefit of clubs and schools, as one of its key priorities," he said.
"The sale of the lands at Newlands, acquired by the IRFU between 1994 and 1996, has been identified for some time as imperative to delivering on this objective.
"It will now allow the Union the opportunity to progress investment options which will, in addition to securing a new realisable asset, produce an additional, long-term income stream to support further development of the domestic grassroots game on this island, in the decades to come.
"It is also envisaged that a portion of the proceeds will be provided for new club and playing facilities development programmes."