Mimi is a very minor female Peanuts character who has never appeared in the strip, but she does appear in the TV special, It Was My Best Birthday Ever, Charlie Brown. She was voiced by Jamie Cronin, who also voiced Lucy van Pelt in the same special, and her singing voice was done by Cathy Cavadini.
On his way home from a birthday party, Linus overhears beautiful singing coming from a garden. He enters the garden looking for whoever's singing the song. He then finds a little blonde haired girl name Mimi. Linus becomes attracted to her because of her beautiful singing voice. She is staying at her grandma's house for a week when Linus, who was on his way home at the time, meets her. She teaches Linus about flowers, telling him that she finds flowers fascinating. Linus invites her to his upcoming birthday party.
Linus cannot get her off of his mind. He constantly thinks about her and her beautiful voice. She does not show up at his party right away, which makes Linus very anxious. At the end, however, she does show up, sings "Happy Birthday" to Linus, kisses him, and hands him a flower much to his delight, before she leaves.
She was introduced in the town simulator game Snoopy's Town Tale in 2018 as part of the Easter. Here, she retains her appearance from the TV special. However, she was removed from the game in 2019 due to copyright issues. She, alongside Polly and Dolores are the only non-comic strip characters to be released in the game.
Mimi is shown to be very courteous and kind-hearted little girl. She is also a horticulturist as she likes flowers, hence her working in the garden at the time. She also likes to sing.
Mimi has medium-length golden blonde hair and blue eyes. She wears a beige sun hat with a magenta ribbon around it, a purple dress with a white apron and matching purple shoes. Her hair is held in short pigtails, and she is about as big as Linus himself is. Her color scheme is similar to Janice Emmons's.
She retains her original appearance in Snoopy's Town Tale, except her hat is white and her dress and shoes are colored pink.
- She is the last character to be introduced in a TV special.
- Her singing voice was done by Cathy Cavadini, who was the voice of Blossom on the original Powerpuff Girls.
- She bares a striking resemblance to both Dolly and Janice Emmons.
- She is the third girl to kiss Linus; the first was Sally and the second was Eudora.
- She is the first, and so far only Peanuts character to have a known eye color, as she has blue eyes.
- She is one of the many Peanuts characters to wear their hair in pigtails. The others being Violet, Sophie, the Little Pigtailed Girl, Dolly and Nell.
- Despite being removed from the market in Snoopy's Town Tale, Mimi still appears in the game if the player doesn't removed the game on their mobile device or if the player updates the game to the latest version.
- She is the third girl to return Linus's affections. The first being Mary Jo and the second was Janice.
- She is one of the many characters in the series to have a pointed nose. The others are Frieda, Lila, Lydia, Peggy Jean, Babette, Jaques, Dolly, Janice Emmons, Melody-Melody, Evelyn, Mary Jo, Nell, The Four Princesses, The Cheerleading Squad, Charlotte Braun, C.A.R.A. and Heather.