Mustafa easily gets nervous when dealing with demanding customers and critics, trying his best to please them. When the customers ask if Linguini has anything new, Mustafa panics and tells the kitchen crew of the request. Chef Skinner is shocked to learn from Mustafa that the customers want food specifically from Linguini, so he, out of spite, deceives Linguini into cooking one of Gusteau's failed recipes. Fortunately, Remy improves it and Mustafa returns greatly excited. The customers love the food and now all want the same dish.
After Linguini discovers that he is Gusteau's son, he becomes head chef and fires Skinner. Mustafa, similar everybody else, likes this change of leadership, and gleefully participates in the burning down of all of the frozen foods that were going to be distributed in Gusteau's name. When Anton Ego arrives to test Linguini, Mustafa again gets nervous and finds himself at Ego's mercy, unable to understand the nature of Ego's dinner request. Ego gives up and insists that Linguini "hit him with his best shot."
Mustafa later discovers, along with everybody else, that Linguini is not the chef, but that Remy is. When Linguini suggests that they follow Remy instead, Mustafa is unable to believe that Linguini who was considered one of the best chefs in Paris has been taking credit for the work of a lowly rat and leaves him with the others.
He is the least recognizable of John Ratzenberger's roles due to being voiced in a French accent.