Nanny is hired by Roger and Anita Radcliffe as a cook-and-housekeeper, although the Radcliffes seem to see her more as a member of the family than a servant. Within only a few months, she becomes very close to the family and is especially joyful when the puppies finally arrive. When Cruella De Vil visits to offer a buying price for the newborn puppies, she joins Roger and Anita in standing up to her and subsequently to refuse her offer. She even called Roger a blooming hero for his bravery. Nanny's primarily responsible for watching the puppies when the Radcliffes aren't around, such as when they're on walks with Pongo and Perdita. During this time, she grows quite attached to the young dogs. One night, while Roger and Anita are out, Jasper and Horace arrive to steal the puppies for Cruella, posing as electricians to gain entry. Nanny isn't fooled by their ruse and refuses to let them in with the masters of the house gone. The two crooks ram their way into the house and although she puts up a tough fight, Jasper holds her in the attic (while Nanny tosses a teapot at Jasper) while Horace abducts the puppies. After the two thieves leave, she runs downstairs expecting to see the family valuables gone, but discovers the puppies have been stolen instead, to her horror. She runs out into the street, hysterically calling for help.
Apart from being seen in a newspaper photo, sitting solemnly by the vacant puppy basket, Nanny is not seen again until the end of the movie, just before the puppies return home at Christmas. She serves tea to Roger and Anita as she weeps over remembering the puppies, but hurries at once to open the door when she hears the familiar sound of barking. Even though the dalmatians scatter ashes and soot all over the apartment and its inhabitants from their disguise to hide from Cruella and the Baduns, Nanny's never happier to be reunited with them and dusts them off so they can be recognized.
When Roger and Anita moved to the farm, she continues her duties as their housekeeper, she picks up the newspaper and puts it on the laundry basket, but puts it down near the hole into the music room when she hears the kettle boiling. When Jasper and Horace come to steal the puppies, Nanny hears the Kanine Krunchies theme, playing from the van. She confronts the Badduns by hitting them with a frying pan; however, they chase her through a pigsty. The Badduns tie Nanny up and lower her down a well.
She is later rescued by the police, and she arrives with them to identify the Baduns as the ones who stole the puppies. The Baduns point out that it was Cruella who made them do it and is behind of the dognapping.
Nanny appears as one of the main characters in 101 Dalmatians: The Series.
In "Home is Where the Bark Is", she gets mugged, and the muggers take her purse whilst walking the puppies, but Lucky retrieves it. This act is what convinces Roger that it's time to move out of the city and to the country.
She does numerous chores on the farm, such as using a bicycle attached to the Chow Tower to pour out the pups' kibble. Other chores include gardening, painting, housework and getting rid of Cruella's surveillance cameras.
She also mentions her family sometimes. In "Southern Fried Cruella", it is said she has a sister named Franny, whom she later visits in "Leisure Lawsuit". Another family member she mentions is her brother, whom, she tells Horace, is a cop.
The series also establishes a relationship between her and Horace, first spawning when Horace tells Nanny that she has beautiful eyes in "Home is Where the Bark Is". In "Frisky Business", Horace tries to help her, but she turns him down. However, when they work together to get Lucky, Rolly, Cadpig, Spot, and Cruella's car returned, Nanny gives Horace a kiss on the cheek. Horace then makes her a Valentine cake in "Valentine Daze". Nanny slams the door in his face when he greets her, but once she learns what Horace intended to give her, the two have tea together.
Another person who falls in love with Nanny is the Baron in "Cupid Pups". He claims when he tasted his boiled radish in pickle sauce, he knew she was the one. He proposes to her, but she turns him down since someone's got to look after the Dearlys. The Baron takes it easy, figuring it's for the best, but requests some radishes to go.
Nanny has also achieved the honor of "Humanitarian of the Year".
In 101 Dalmatians, it is said that Nanny used to be Anita's Nanny. She recalls that Anita was always good at drawing when she was a little girl and is now pleased to be working for Anita again as she starts a family of her own. She is the first to realize that Perdita is expecting with pups and when she notices Anita demonstrating all the same signs, she finds out Anita is pregnant too.
When the Puppies are born, she brings the towels downstairs for Perdita and informs Roger and Pongo about their arrival. When Roger brings a stillborn pup back to life, she names it Lucky. She later arrives to give the Puppies their collars.
On the night the Puppies are abducted while Roger and Anita are gone for a walk to the park (while also taking Pongo and Perdy with them), she was putting some unfinished dog food in a pot ("Waste not, want not, that's my motto").
When Horace and Jasper arrive, she does her best to fight back and manages to punch Horace in the face. However, they lock her in a cupboard under the stairs. Nanny manages to break free and looks at the basket where the puppies are, realizing that Jasper and Horace stole the puppies. Then, Roger, Anita, Pongo, and Perdy arrive hearing the Pensioner's bulldog barking angrily at Jasper and Horace; Nanny explains that she tried to stop the two, but they locked her in the cupboard, and she shouted, but no one came to stop them. Roger and Anita then realize the mistake they made in leaving the puppies unprotected, and call the police and the Pensioner, who then explain to them. During the Twilight Bark scene, Nanny is seen to bark in her sleep.
When Pongo and Perdita run off to find the Puppies, Nanny is able to guess why they did so and agrees with Roger's suspicion of Cruella being the culprit. When she notes that dogs can smell ill intentions, Anita suddenly realizes that Roger is right about Cruella and her motivation.
When the Puppies are returned and the Dearly's are offered to keep them, Nanny figures they have seventeen already, so adding some more would be a good idea.
In the end, she moves in with Roger and Anita, when they move to the country.