Casey was raised in Oakville, Ontario. His father, Richard, is an urologist, and his mother, Patrice, is an image consultant. After graduating from Oakville Trafalgar High School, Casey graduated from McGill University with a Bachelor of Science degree in 2005 and received a Master of Economics degree from the University of Toronto.
Casey relocated to Los Angeles, California for his career in January 2009. Over the next few years he attained guest roles on shows including Warehouse 13 and The Vampire Diaries and recurring roles on Valemont, Being Erica, and Skins. In July 2011, Casey appeared as Brad in a notable episode of Torchwood: Miracle Day, titled "Dead of Night". In 2011, he was cast as Navy SEAL Sean Pierce in the action show Nikita. Casey's part was initially intended to be a short term recurring role, but was upgraded to a series regular.
He obtained his first lead role for the movie Creature which was released in September 2011 and was unsuccessful at the box office. In 2012, Casey was cast in The Vow, which was successful at the box office as the fourth-highest weekend debut of 2012.
Casey starred in the 2013 digital series Backpackers, and in the 2014-2015 TV drama Remedy. In 2016, Casey guest starred in Marvel's Agents of S.H.I.E.L.D., appearing in the episodes 4,722 Hours and Maveth as Astronaut Will Daniels.
