Frustrated with the lack of opportunities in New Zealand, he moved to Sydney, Australia for six weeks in 2001, before returning to his native Canada for two months, where he worked as a waiter and dishwasher until deciding to move to Los Angeles, USA.
Since 2002, Gillies has worked in Canadian and American film and television - at times simultaneously. Before landing lead roles in television series, Gillies landed guests spots on television shows such as Masters of Horror, NCIS, and True Blood. In 2010, he was cast on the hit The CW drama The Vampire Diaries as Elijah Mikaelson. In 2013, CW created a successful spin-off of The Vampire Diaries chronicling the lives of the first (aka "the Original") vampires. Gillies' once recurring part as Elijah from The Vampire Diaries became a lead part in The Originals. A potential nightmare existed for CW since Gillies was already under contract to play the playboy-ish Dr. Joel Goran in the supernatural series, Saving Hope. Saving Hope initially aired in the US on NBC, but the series was not renewed although it continued to run in Canada. He continued both shows. In 2012, Gillies wrote, directed and starred with his wife Rachel Leigh Cook in Broken Kingdom.