The family lives in happiness for several years, until the death of Ella's beloved father. After that, Lady Lorna's true nature is revealed, and she and her spiteful daughters take over the estate, and begin to abuse and mistreat Ella, envious of her beauty. She is forced into housekeeping responsibilities and made to wait upon her jealous stepsisters like a maid. As Ella blossoms into a beautiful young woman who is kind despite her hardships, she befriends the animals living in the barn, including Bruno the Pitbull, Major the horse, and many of the mice and birds who live in and around the chateau. Ella finds a mouse inside a trap, releases him, and names him Gus (his real name is Octavius). She is also friends with a mouse named Jaq, the leader of a mouse-pack. ("A Dream Is a Wish Your Heart Makes")
At the royal palace, the King is angry that his son does not intend to marry. The King is determined to see grandchildren, so he and the Duke organize a ball for Prince Charming in an effort to cause his son to fall in love and marry, with every eligible maiden in the kingdom ordered to attend.
When the invitation to the ball arrives, Ella asks her stepmother if she can attend. Her stepmother tells her she may go to the ball, if she finishes her work and can find a suitable gown. To consume her time, her stepmother sets Ella up with a mountain of chores. ("R-E-S-P-E-C-T!") Her mouse friends Gus and Jaq use Ella's stepsister's discarded sash and beads to fix an old gown that belonged to Ella's mother. When Ella wears her dress before the ball, Lady Lorna subtly points out her daughters' beads and sash, and the angered stepsisters tear the gown to shreds, leaving Ella to run to the back of the garden in tears while her stepfamily attends the royal ball without her. ("If I Could Go Dancing")
Ella's Fairy Godmother appears to her in the garden, and transforms her appearance for the ball. She transforms the mice into horses, Bruno the dog into a footman, Major the horse into a coachman, a pumpkin into a carriage, and transforms her torn dress into a beautiful purple dress with glass slippers. Ella departs for the ball after the fairy godmother warns her that the spell will expire at the stroke of midnight. At the ball, the Prince rejects every girl, until he sees Ella, with whom he is immediately smitten. The two dance throughout the castle grounds until the clock starts to chime midnight. Ella flees to her coach and away from the castle, accidentally dropping one of her glass slippers. After the Duke tells the King of the disaster, they plan to find Ella with the slipper they found during her escape. The next morning, a royal proclamation is issued, stating the Grand Duke will visit every house in the kingdom to find the girl who fits the glass slipper, so that she can be married to the Prince. When this news reaches Ella's household, her stepmother and stepsisters begin preparing for the Grand Duke's arrival. Ella, overhearing, begins dreamily humming the song from the palace ball the previous night. Realizing Ella was the girl who danced with the Prince, her stepmother follows Ella up to her attic bedroom and locks her inside.
When the Grand Duke arrives, the mice steal the key to Ella's room from Lady Lorna's pocket and laboriously drag the key up the stairs to her room, only barely managing to free her after a fight with the stepmother's cat Lucifer, in which Bruno comes to their rescue and scares the evil cat out of the house. Meanwhile, the stepsisters try on the slipper, but their feet are too large. As the Duke prepares to leave, Ella appears at the top of the stairs, asking to try on the slipper. Knowing that the slipper will fit and that Ella will marry the Prince, Her stepmother trips the footman over while he is carrying the slipper, causing it to drop and shatter on the floor. Ella then reveals she has the other glass slipper. Delighted at this indisputable proof of the maiden's identity, the Duke slides the slipper onto her foot, which fits perfectly. The two agree to keep the broken slipper a secret.
At the wedding, Ella and the Prince descend the church's staircase, surrounded by confetti tossed by the King, the Grand Duke and the mice, now in uniform apparently as part of the Royal Guard. As the film ends on a scene of the two newly-weds kissing.
In a post credits scene, the stepmother and her two daughters are put in jail.