A New York City poet named Archy (Eddie Bracken) attempts suicide only to come back as a cockroach. As he learns how to write poetry by hopping on typewriter keys, he grows used to his new life and becomes infatuated with Mehitabel (Carol Channing), the singing alley cat. She instead goes out with the tomcat Big Bill (Alan Reed). When Big Bill dumps Mehitabel, Archy confronts her about her wild ways in general and her affinity for bad boy tomcats in particular. She momentarily agrees; however, self-appointed theatre maestro cat Tyrone T. Tattersall (John Carradine) promises to make her a star and becomes her next lover. Archy attempts and fails suicide again. In the theatre, Mehitabel holds up her end of the deal in getting food for Tyrone, but he kicks her off the stage. Archy and Big Bill watch her, and Mehitabel gets back together with Big Bill. Back to his typewriter, Archy channels his frustration in calling the other insects and spiders to revolution. He immediately drops the scheme when he hears the news that Mehitabel has kittens, and Big Bill has left the scene again. It's a rainy evening, and Archy points out to Mehitabel, that her kittens, who are inside a cover less trashcan, are floating away from her, and the two of them rescue the kittens, however, a moody Mehitabel, chases Archy away for interfering with her private business. Archy persuades Mehitabel to give up her life as an alley cat and support the kittens with a "job" as a house cat. Later, however, when Archy comes to visit her in the upscale house, with her visibly changed by the experience, she reminds him that social class now separates them from being friends and kicks him out—regretting it later. Archy gets drunk and meets several ladybug street walkers who find his love poems about Mehitabel. Big Bill makes fun of him. One day, Mehitabel returns to Shinbone Alley and sings and dances again like her old self. After having tried to reform her, Archy realizes he liked Mehitabel for her wild ways all along and accepts her for "being what she has to be," content to be just friends.