Mitzie is a pale skinned girl that has long brownish red hair, done up in pigtails. She wears Hawaiian themed clothes with a sleeveless white shirt with light red flowers on it and teal shorts with green shoes and white socks, while in school, for special occasions, she wears a suit that consists of a black tuxedo with a red bowtie, a grey skirt and black shoes. Mitzie's voice is similar to Tanya Mousekewitz from An American Tail: Fievel Goes West.
Mitzie is more mature than her brother, Marty. She is honest and caring to her family and friends, and, much like her friends, hates being babysat by Robot Vicky. Mitzie also has a crush on Greg Prestonovich. Although, she sometimes can be a bit impulsive and clumsy on a few occasions. Mitzie also knows martial arts such as kung-fu and karate, thanks to Celia James and her mother Charlotte. She is also a vegetarian. Mitzie is sometimes described by her friends as a "living lie detector", as she can tell if a person is lying or not. She is good friends with Jessie Prestonovich, Tammy Turner and Celia James.