The series consists of 39 half-hour episodes divided into three seasons. The first two seasons consist of 13 episodes with a full 22-minute story each, while the third season consists of 13 episodes divided into 26 11-minute stories.
Mimi Mortin (voiced by Chiara Zanni) - A red-haired 11-year old girl in the sixth grade. She's clever, optimistic, and has a powerful imagination. She's always willing to help and solve any problem that she may encounter, most of the times with creative plans and ideas. Although her plans may not always work out the way she expects them, Mimi receives a lot of help from her best friends Elaine and Russell, her family, and even her rivals, and finds a way to solve any problem.
Elaine Pituskin (voiced by Kori Cook) - Mimi's best friend who is of Asian descent (presumably Japanese or Chinese). She is an animal and nature lover, and owns lots of pets. She can be temperamental and argue with Mimi at times, but she always looks up to Mimi as her best friend, in turn, Mimi respects her a lot.
Russell Van Eden (voiced by Rhys Huber) - Mimi's other best friend and sidekick. A boy with blonde hair and blue eyes, who is a sports lover, although he is a bit clumsy. He has skills with his video camera and aspires to be a film director. He is shown to have a crush on Sincerity early in the series but his interest on her fades away by the end, instead hinting at being attracted to Mimi.
Sincerity Travers (voiced by Carly McKillip) - A snobbish preppy teenybopper with pink hair who, sometimes, does not get along with Mimi. She and Mimi used to be friends years ago, but as they got older, their interests diverged, and they started growing apart. She is Mimi's rival in school, and although she does not get along with her, she admits that her ideas are pretty good and helps with some of her schemes. Even if she does not get along with Mimi, she has a resentful respect for her, showing that deep inside, Sincerity still considers her a true friend.
Brock Wickersham (voiced by Tony Sampson) - A bully who enjoys pulling pranks on various characters, especially on Herbert Finkle. He sometimes shows a misogynistic attitude, such as when he threatened to beat up Mimi in the episode Leapfrog.
Budweiser "Buddy" Wickersham (voiced by Andrew Francis) - Brock's younger brother who is also a bully. It is also revealed that he is a genius, but he does not want people to find out about it, especially his big brother, saying that that fact would embarrass him in front of his family.
Brad "Bradley" Mortin (voiced by Keith Miller) - Mimi's 7-year old brother who knows that Mimi's plans always have flaws.
Jason Mortin (voiced by Samuel Vincent) - Mimi's 16-year old teenage brother who thinks of himself as an on-the-edge rebel.
Saffron Mortin (voiced by Pam Ferris) - Mimi's mother. She is a vegan, and always feeds her children vegetables.
Marvin "Marv" Mortin (voiced by Ray Ray F.R.) - Mimi's father.
Hayley Kitchensinker - Sincerity's "lackey", although she is kind and many times disagrees with Sincerity, and is good friends with Mimi, Elaine and Russell.
Herbert Finkle - A nerd at Mimi's school who is of Russian descent. He is in charge of the school newspaper. He's also often the target of Brock and Buddy's pranks.
Lodeman - A student at Mimi's school who tends to make rude noises and to act distracted all the time.
Ms. Victoria Frances Grindstone (voiced by Mindy Sterling) - Mimi's teacher.
Mr. Petri - A science teacher who blames Brock for everything bad (even over things Brock never did) because of his state of being a bully and for pulling multiple pranks inside of his classroom.
Mr. Jacques - A gym teacher.
Ms. Murchison - The librarian of Starfish Bay School. She and Mr. Pianoforte hate each other.
Principal Earl - The principal of Starfish Bay School.
Mr. Pianoforte - A music teacher. He and Ms. Murchison hate each other.
Note: 2 volumes of the show have been released on DVD by Anchor Bay Entertainment. Volume 1 includes four half-hour episodes and one 11-minute episode. Volume 2 includes three half-hour episodes and three 11-minute episodes.