The rest of the squad and staff members all tested negative, with the FAI confirming that the player had no close contacts in the group.
"The Football Association of Ireland can confirm that one member of the senior men's international team has tested positive for COVID-19," a statement said.
"The player has been isolated from the group as per COVID-19 protocols, and the HSE and UEFA have been informed of this development. The player is asymptomatic and feeling well.