Simon Coveney will attend an event marking the centenary of the creation of Northern Ireland.
The Government says the Foreign Affairs Minister will be accompanied by the Chief Whip, Jack Chambers.
President Michael D Higgins previously declined an invitation to the church service in Co Armagh, saying the title of it was politicised - and noting that would be inappropriate for the Head of State to attend an event that commemorates partition.
The invitation is to a "service of reflection and hope to mark the centenary of the partition of Ireland and the formation of Northern Ireland".
Britain's Queen Elizabeth II is also due to attend the event later this month.
In a statement, the Government says its role in this "is clearly distinct from that of the President."
"In that regard, the Government reiterates its full support and understanding for the decision made by President Higgins with regard to his attendance at the event.
"That decision was quite properly made by the President, and was based on concerns that he had consistently expressed."
But the statement adds: "Cognisant of that important distinction, and in recognition also of the spirit and intentions of the church leaders in organising the event, the Government has decided that it will be represented at the event by the Minister for Foreign Affairs and by the Government Chief Whip."