Colette is the only female cook in Chef Skinner's kitchen at Gusteau's. She is a capable cook, hard working and very tough to enter the masculine world of haute cuisine. She had defended Linguini from being fired as a garbage boy when Skinner caught him "cooking" the soup in which Remy had made. She takes Linguini under her wing and teaches him the skills necessary to survive in the fast-paced kitchen. She was at first unaware of Luigini's admiration for her. Colette felt disgruntled when Skinner took a personal interest into Linguini, which in fact Skinner was trying to force the truth of Linguini's cooking.
The next day, she tells a sleepwalking Linguini (puppeteered by Remy at the time) that she likes him, and storms out after mistaking his lack of reaction for snobbishness. Linguini awakes, and struggles to tell her the truth. Colette is initially puzzled by his actions and raving behavior, and slips a hand into her bag for a canister of mace. Remy desperately makes Linguini fall onto Colette to prevent him from talking further and the two kiss. Colette is equally surprised as Linguini but quickly falls in love, dropping the mace. A romantic relationship quickly blossoms after this incident.
When Linguini suddenly inherits the restaurant when Remy successfully steals papers and will that testify that Linguini is Gusteau's secret son, he and Colette runs the restaurant. Food critic Anton Ego arrives with a challenge for the restaurant, and Colette prepares only to discover that Linguini had no ability to cook. When Linguini defends Remy, Colette listens to his claim that the rat is the real cook. Tearfully, she believes that Linguini has lost it, and so leaves him. However, she remembers Gusteau's motto: "Anyone can cook" (a phrase she deeply believes in) and returns to aid Linguini and Remy in the cooking.
Ego is successfully dealt with, and he requests to see the chef. Reluctantly, she allows Remy to be unveiled as the true chef and Ego leaves, reformed. Later, Gusteau's was closed down due to rats in the kitchen, but Colette is found cooking at a new Parisian bistro, along with Linguini and Remy, with Ego as a patron and queues stretching around the block.
- Aside from being the only female chef in Gusteau's Restaurant, she is also the only main female character in Ratatouille.
- In Your Friend the Rat, there is a scene where Remy is holding hands with a little girl that looks like her.
- Colette is the second sole female main character of a Disney film (and of one that is CGI-animated) to be voiced by Janeane Garofalo, the first being Bridget in The Wild.
- She is the first character to train a protagonist in something (in this case, teachs Linguini how to cook), being Remy the second, that does so, and Wreck-It Ralph the third (teaches Vanellope von Schweetz how to race).