The alley cats are a jazz band: Shun Gon (Chinese Cat) plays the piano and drums made out of pots, Hit Cat (English Cat) plays the acoustic guitar, Peppo (Italian Cat) plays the concertina, Billy Boss (Russian Cat) plays the bass, and their boss Scat Cat plays the trumpet. Together, they play jazz music while their boss usually sings.
The alley cats are first seen after Thomas O'Malley leads Duchess and her weary kittens to his penthouse, where jazz music can be heard from inside. Duchess still insists on spending the night here, so O'Malley allows them to stay and introduces his friends, Scat Cat and his gang of alley cats, making lively music together. While playing their instruments, the alley cats and their boss all sing "Everybody Wants to Be a Cat". O'Malley and Duchess join in the fun, as do Berlioz, Marie and Toulouse. During the song, O'Malley and Duchess perform a dance number, and Duchess sings a wonderful solo while playing the harp; which the alley cats find so beautiful, soft, lovely, and romantic until they get back to playing their instruments (with the help of Scat Cat's trumpeting) and make their way out of the penthouse along with other alley cats.
The alley cats are seen again when Roquefort meets with them and tries to get them to help save Duchess and her kittens from Edgar, but is unable to remember O'Malley's name. The alley cats prepare to eat him, but Roquefort yells out the proper name in frustration when asked for last words. The alley cats head off to help O'Malley, leaving Roquefort to chase them down in an attempt to lead them to the correct house. Coincidentally, this also led to a Frenchman to consider giving up wine after he witnessed a mouse (Roquefort) seemingly chasing the cats. Believing he was hallucinating, the Frenchman poured his wine onto the ground.
The alley cats reappear when Edgar attempts to ship Duchess and her kittens to Timbuktu. They pile on top of the butler, screeching and clawing, while Roquefort manages to release Duchess's family by cracking the trunk's combination lock, abruptly yelling for silence in order to hear better. The alley cats defeat Edgar by locking him in the trunk and pushing it outside. The alley cats then watch as Edgar is shipped off to Timbuktu instead.
The alley cats are last seen in Madame Bonfamille's mansion, which she opens up to all the alley cats of Paris. Scat Cat and his alley cats celebrate by playing their instruments around the grand piano in Madame's piano room downstairs, singing a reprise of "Everybody Wants to Be a Cat".
In the show, Scat Cat, O'Malley, and the other alley cats were all a part of the popular band "O'Malley and the Alley Cats." However, as a running gag in the show, something or someone would prevent the band from playing.
- The way the alley cats initally teased Roquefort and embarrassed him is similar to how Elena, Teresa and Yuki treat Lilo and Stitch in the Lilo & Stitch franchise.
- Shun Gon (the Chinese Cat) bears a close resemblance to Si and Am from Lady and the Tramp, and shares the same voice actor as Boomer in The Fox and the Hound and Tigger from the Winnie the Pooh franchise.