Alonzo is first seen when Cruella enters the House of DeVil at the start of the live-action film, busy trying to direct several phone calls coming in at once, and quite panicked as a result. However, he still stands up to greet Cruella.
When Cruella takes Anita to her office, she scolds Alonzo by reminding him to ask Anita if she wanted a drink. She then shouts at him when he hesitates to take the drawing from Anita and give it to her. Once he does, Cruella tells him to stand somewhere till she needs him. He is then ordered to give the drawing back to Anita when Cruella makes an addition to the design.
He is later seen at Cruella's home, when Horace and Jasper present the tiger skin coat to Cruella. His hands are shown to have a nervous shake as he pours them tea.
After Cruella was released from prison, reformed by Dr. Pavlov's threapy, Alonzo greeted her with a gift - a Chinese crested dog whom she named Fluffy. As soon as Cruella arrived back at her house, he was given the job of burying all her furs in an underground chamber, including her design for the Dalmatian puppy coat. Subsequently, he helped her working with the dogs at Second Chance dog shelter.
When Cruella was reverted back to normal, Alonzo, desperate to please her, was sent out to steal the puppies needed for her coat, while she met with furrier Jean-Pierre Le Pelt. When he showed up with the captured puppies, Le Pelt took an instant dislike to him, calling him a wormy little man. Alonzo also was landed with the job of looking after Fluffy, as Cruella was back to her dog-hating ways. Alonzo also helped place evidence and Dalmatian puppies to frame Kevin Shepherd - the owner of the Second Chance dog shelter - for the crime, and then to steal the puppies back from under the police's noses. Upon arriving at the train station, which was taking Cruella, Le Pelt, and the captured Dalmatians to Paris, Alonzo was tasked with eliminating Oddball, as Cruella only wanted spotted puppies for her coat. When Oddball managed to elude him, resulting in Alonzo getting his hands run over by a baggage trolley, he gave up and returned to the train, telling Cruella she'd never see Oddball again.
After arriving in Paris, Alonzo's resentment of Le Pelt grew when the furrier got to ride in Cruella's car while he had to follow in the van with the puppies. He was present when Cruella trapped Kevin and Chloe Simon - Cruella's probation officer - in the basement of Le Pelt's sweatshop. Once inside, Alonzo was the first to notice the puppies escaping, although he tried to cover the fact. When Cruella noticed, she yelled at him for not killing Oddball, then stormed off to recapture the puppies, causing Le Pelt to jeer at him again. Finally fed up, Alonzo engaged Le Pelt in hand-to-hand combat, resulting in Le Pelt becoming trapped in the hole through which the puppies had escaped. Alonzo then freed Kevin and Chloe.
Later, Alonzo showed up at the Second Chance dog shelter with eight million pounds for the shelter - on the judge's orders, all of Cruella's money had gone to the dogs' homes of the borough of Westminster - of which "Second Chance" was the only one. While what happened to Alonzo subsequently is unconfirmed, it could be assumed that he started working at "Second Chance" as well.
101 Dalmatians: Animated Storybook
Alonzo makes a small cameo on the second page of 101 Dalmatians: Animated Storybook. If the player clicks on a buzzer, Cruella shall press it and order Alonzo to get to where she is. When he arrives, Cruella asks what took him so long, and he apologizes for it. Cruella then tells him to stand somewhere till she needs him, and he walks off.
101 Dalmatians: The Series
Whilst this is yet unconfirmed, in the series episode "Barnboozled", when Cruella moves into the barn, she demands to know where her cappuccino maker is, and a butler, having a similar resemblance to Alonzo, appears. He is later seen taking Cadpig's squeaky toy from her, when Cruella (annoyed by its noise) demands to have it.
- Alonzo did not appear in the original animated 1961 film nor its sequel. He was created specifically for the live-action version of this film and its sequel, 102 Dalmatians.