Nemisz was a first round selection, 25th overall, at the 2008 NHL Entry Draft by the Calgary Flames and made his NHL debut with the Flames in 2011. Nemisz spent the majority of his career in the American Hockey League (AHL) with Calgary's affiliate, the Abbotsford Heat, and then the Charlotte Checkers, affiliate of the NHL's Carolina Hurricanes. Internationally, Nemisz was a member of Team Canada's silver medal winning squad at the 2010 World Junior Ice Hockey Championships. He retired as a player in 2015 to become an assistant coach of the Oshawa Generals.