His film roles include the comedy-drama It's Kind of a Funny Story (2010) and the supernatural horror It Follows (2014).

[6][7] Gilchrist spent his early years in London, before relocating to Boston, Massachusetts, during his childhood,[8] then to New York City, before finally settling in Toronto, Ontario.

From 2009 until its ending in 2011, Gilchrist co-starred as Marshall Gregson, the son of the lead character, on the Showtime comedy-drama series United States of Tara.

In 2015, he played the lead role of Daniel Austin in the film Dark Summer,[11] starred as John Lovett in The Stanford Prison Experiment and William in Len and Company, and had a role in the short drama film Share.

In August of that year, he starred as Sam Gardner, a teen on the autism spectrum who is ready to have a girlfriend, in the Netflix comedy-drama Atypical.