In the first film, Mike is Sulley's best friend and working partner at Monsters, Inc.. He supports Sulley about being the number one scarer, and both are enemies of Randall Boggs. He is also Celia Mae's boyfriend and seems to be watched at by Roz who awaits for his paperwork. While at Harryhausen's for Celia's birthday, Sulley appeared out of nowhere to tell Mike that he had lead a human girl into the monster world. Putting her into a Monsters, Inc. gym bag, Sulley tried to show him, but the human girl got out of the bag and wreaked havoc all over the restaurant. The two secretly took her out before the CDA found her and disinfected the entire restaurant.

When Mr. Waternoose throws Sulley and Mike into the frozen wasteland, a rift forms between them after Mike gets mad at him for listening to Waternoose instead of him.

When they learn that Randall and Waternoose are in on a scam of draining children of screams, Sulley tricks Mr. Waternoose into confessing Randall's plan and him working as Randall's henchman while Mike records the confession and smugly replays it to watching CDA agents. Immediately, the CDA turn on Mr. Waternoose and arrest him for being in cahoots with Randall. Once Boo is back in her room, Mike rebuilds her door that the CDA destroyed so Sulley will be happy again.

Sometime after the film, Mike's low-budget company play "Put That Thing Back Where It Came From or So Help Me" that he has starred in, written, directed, and produced comes in front of the audiences.