 O'Neill became a regular starter in 2013 and received strong reviews, earning the Rapids' Young Player of the Year award and a nomination for U.S. Soccer Young Athlete of the Year as the Rapids returned to the playoffs.His first career goal came in a 4–1 home win over Montreal Impact on May 25, 2014.On August 7, 2015, O'Neill was bought by Cypriot club Apollon Limassol for an undisclosed fee.