[6] Demetriou's student revue show Bristol Revunions received critical acclaim at the Edinburgh Fringe Festival from 2009 to 2011.

[8] Comedic television acting credits include Scrotal Recall, Drunk History,[9] Tracey Ullman's Show, Fleabag, and Channel 4 sitcom Stath Lets Flats in which he stars with his sister Natasia Demetriou.

Stath Lets Flats was also written by Jamie (with the first three episodes co-written by Look Around You and Friday Night Dinner creator Robert Popper) and also stars Katy Wix and Dustin Demri-Burns.

[15] Demetriou voiced Moriarty in the 2018 animated film Sherlock Gnomes, opposite Johnny Depp as the eponymous detective,[16] and appeared in the music video for "Nightmares" by Easy Life.

In 2020, he appeared in The Great alongside Elle Fanning, the comedy TV series Miracle Workers, and played a small role in Eurovision Song Contest: The Story of Fire Saga.