 O'Neill is eligible to represent both the United States and the Republic of Ireland.On October 9, 2012, O'Neill was called up by the United States U20 national team for the 2012 Marbella Cup in Spain.A day later, O'Neill made his debut for the U20s in a 2–1 loss to Canada, however he suffered an eye injury that ruled him out for the rest of the tournament.