Aside from acting, Adler has also worked as a teacher, a janitor and caretaker in a church, a house renovator/painter, a baker for a house of ill repute, a graphic artist and a nude model at the Art Students League in New York, and is currently working on his degree in naturopathy and contact reflexology.
Adler's most famous voice credits include The Smurfs, Tiny Toon Adventures, Cow and Chicken, AAAHH!!! Real Monsters!, I Am Weasel and Rocko's Modern Life. In Cow and Chicken, Adler provided the voices for the three major characters (and also I. R. Baboon in the I Am Weasel shorts featured with each episode). This is unusual in contemporary animation, though Mel Blanc would commonly do this in the "golden age" of Warner Bros. animation.
He has recently achieved fame for starring in Michael Bay's 2007 live-action film Transformers and its 2009 sequel, Transformers: Revenge of the Fallen, providing the voice of Starscream, after having voiced the characters of Silverbolt and Triggerhappy in the 1980s Transformers animated series. Just as Chris Latta voiced both Starscream and Cobra Commander in the Sunbow cartoons, Charlie Adler also was the voice of Cobra Commander in G.I. Joe: Resolute.