Conor McGregor will face Jose Aldo in Las Vegas on July 11.
McGregor has said he will defend the title in Ireland 'once' he beats Aldo. His Brazilian opponent is unbeaten since 2005 and has won 18 fights in a row.
It will serve as the showcase fight for the International Fight Week which runs from 7-15 July.
See also: Conor McGregor Names His Top 3 Irish Sporting Heroes