Mayo and Galway will play out their Connacht final on Sunday week in Croke Park.
Connacht GAA has taken the decision to avail of the extra capacity in the capital.
The Leinster hurling final and football semi-finals this weekend will have 18,000 capacity.
MacHale Park would have been restricted to a 3,500 capacity, if the game was played there as planned.
It will be the first time that a Connacht football final has been played outside the province.
The game will be played at 1.30 on Sunday week, after consultation with both Mayo and Galway.