Day started by playing the lead role in Dead End, at the Huntington Theatre in Boston. Later, he played Charlie Kelly on the hit FX television series It’s Always Sunny in Philadelphia. Day has also appeared on several other television shows including Law & Order, Third Watch, and Reno 911!. In July 2011, he starred in New Line Cinema’s Horrible Bosses.
In 2013, Day voiced the character Art in the Pixar animated film Monsters University. Furthermore, he had a role in Drew Pearce’s film Hotel Artemis, alongside Jodie Foster, Brian Tyree Henry, Sterling K Brown, and Jenny Slate. As a film director, Day is currently working on his debut on the upcoming comedy El Tonto, alongside Kate Beckinsale, Edie Falco, and John Malkovich.
