These mice wake up in the morning listening to Cinderella sing "A Dream is a Wish Your Heart Makes" as well as helping her dress up for the day. The mice later got some bits of corn for breakfast from Cinderella after Jaq distracts Lucifer so they could reach Cinderella in the garden.
Later, Cinderella shows them her mother's old dress, which she plans to redesign as her dress for the ball. When she is called away by her stepfamily for more work that keeps her occupied for the rest of the day, the mice, along with the birds, take over the duty of redesigning the dress, which they show to Cinderella at the end of the day.
Later, the mice watch in horror and dismay when the Stepsisters destroy Cinderella's dress, and when Cinderella ran out into the garden to weep, two of the mice, Bert and Luke, join Jaq and Gus on trying to console Cinderella. These four mice would later be turned into horses by the Fairy Godmother to take Cinderella to the ball. They returned to their mice forms after the clock struck twelve at midnight.
The next day, after Cinderella was locked in her room by Lady Tremaine to prevent her from revealing herself as Prince Charming's true love, the mice and the birds fought Lucifer for the key, but they were no match to their mortal enemy. The battle finally ended in victory for them when Bruno arrived and chased Lucifer away. They later cheered for Cinderella when she revealed the other glass slipper to the Grand Duke, proving herself as Prince Charming's true love.
At the end of the film, the mice moved to the palace and cheered for Cinderella's wedding with Prince Charming.
The mice help with the Fairy Godmother's stories that set the plot in motion. Jaq, Gus, and Mary had the most prominent role in this film, while the other mice were mainly seen in between each segment, with the exception of a few male mice appearing alongside them in the three shorts.
The mice don't appear in the third movie, Cinderella III: A Twist in Time, with only Jaq and Gus appearing. No official explanation has been given, but fans believe that they were omitted due to budget reasons.
The Mice do not not physically appear in the 2010 video game Kingdom Hearts Birth by Sleep, save for the ones turned into horses by the Fairy Godmother in Terra's story. Assumingly, they may have helped a shrunk-down-to-their-sized Ventus in collecting the materials for Cinderella's mother's dress.