The 25-year-old forward scored 21 goals and 39 assists in 71 games in his first season as a Buffalo Sabre. He played ten games at the World Championships earlier this summer, scoring two goals and six assists.
Canada has one final game Wednesday in Pittsburgh before the World Cup of Hockey officially begins. Canada opens the tournament Saturday against the Czech Republic at 8 p.m. The game can be watched on ESPN News.
O'Reilly joins Jack Eichel (North America), Dmitry Kulikov (Russia) and Rasmus Ristolainen (Finland).