Ella lives with her wealthy, loving parents on a beautiful estate in a peaceful kingdom. From a young age, she is taught by her mother to believe in the existence of magic, allowing her to befriend many animals on the estate, particularly the mice. Everything is perfect until her mother falls ill and dies. On her deathbed, she asks Ella to make her a promise that she will always have courage and show kindness to others. Some time later, her father marries Lady Tremaine, the widow of an old friend, who has two daughters of her own: Drisella and Anastasia. Ella welcomes her new stepfamily, despite the stepsisters' unpleasant attitudes and her need to protect her mouse friends from her stepmother's cat, Lucifer.
Soon after, Ella's father goes abroad on business, promising his stepdaughters gifts of luxury. Ella merely asks for the first branch to brush against his shoulder on the way. While he is gone, Lady Tremaine gradually begins to reveal her true cold, cruel and jealous nature, persuading Ella to sleep in the attic and let Drisella and Anastasia have her room. Soon they receive word that Ella's father has passed away. Desperate for money, Lady Tremaine dismisses the servants and forces Ella to do all their work. Later, she refuses to let Ella eat with the family. One cold evening, Ella sleeps by the fireplace for warmth. The next day, she rises with her face covered in cinders. Her stepsisters consequently mock her as "Cinderella", a taunt in which Lady Tremaine also joins; eventually, even Ella herself starts calling herself that.
Crushed by their cruelty, Ella goes for a ride into the woods, where she encounters a hunting party in pursuit of a stag. She meets one of the hunters, who claims to be an apprentice named Kit who lives in the palace. Unknown to her, he is actually the son of the land's dying king. Despite never learning her name, Kit (a nickname given to him by his father) is enchanted by Ella's charm, kindness, and unique outlook on life and becomes infatuated with her. On learning that he has little time left, the King insists that Kit find a bride at an upcoming ball. Although Kit is arranged to marry Princess Chelina of a neighboring kingdom, he can't get over the mystery girl, and persuades his father to let every eligible maiden in the land attend.
When the ball is announced, the Tremaine family is ecstatic at the prospect of marrying into royalty. However, when Lady Tremaine refuses to buy Ella a new dress, Ella fixes up her mother's old pink dress with help from the mice. On the night of the ball, Ella tries to join her stepfamily on the way out. Lady Tremaine, claiming that her mere presence will disgrace them, goads her daughters into callously tearing Ella's dress to shreds, before leaving without her. Ella runs into the garden in tears and apologizes to her deceased mother, saying that she doesn't know how she can keep her promise of being courageous and kind. She then encounters an old beggar woman, who reveals herself to be her fairy godmother. She uses her magic to reveal her true form, and then turns a pumpkin into a magnificent carriage, four mice into horses, two lizards into footmen, and a goose into a coachman. She then transforms Ella's dress into a gorgeous blue gown, complete with a delicate pair of glass slippers, before sending her on her way to the ball, with the warning that the spell only lasts until the final stroke of midnight.
At the ball, the entire court is entranced by Ella, especially Kit, who had been hoping she would arrive. She wins the coveted first dance with him, whose true identity she is pleasantly surprised to learn. This irritates the Grand Duke, who secretly promised Kit to a specific princess—a fact that Lady Tremaine overhears. After dancing, Ella and Kit tour the palace and grounds together. But before he can learn her name, the clock begins to strike twelve, forcing her to flee and accidentally drop one of her glass shoes on the palace stairs in the process. She manages to get away before the stroke of midnight, and hides the other shoe in her room as a memento, reasonably content that her one night will become a beautiful memory.
Soon after the ball, the King dies, but not before giving his son permission to find the girl and marry her if he wishes. When Kit becomes king, he decrees that every maiden in the kingdom is to try on the shoe. Ella goes to her room to get the other shoe, only to find her stepmother waiting with it in her hand. Lady Tremaine has deduced that Ella is the mystery maiden, and demands to be made the head of the royal household if Ella marries Kit and becomes queen. She also demands that Ella ensure that Drisella and Anastasia get proper husbands. Ella refuses, so Lady Tremaine smashes the shoe and locks her in the attic. She then takes the shattered shoe and identity of the mystery girl to the Grand Duke and convinces him to reward her with the title of countess and advantageous marriages for her daughters. The Duke takes the shattered shoe to the king, hoping to persuade him to forget the mystery girl, but this makes Kit more determined than ever to find her.
The Grand Duke and the captain of the guards lead a mission to try the remaining shoe on all the maidens in the land, but it fits none of them. When they arrive at the Tremaine estate, the shoe fits neither of the stepsisters. The officers turn to leave, only to hear Ella singing "Lavender's Blue" through a window that the mice opened for that purpose. The Grand Duke tries to leave anyway, but one of the men reveals himself to be Kit in disguise, and demands that the captain investigate the sound. Once Ella is found, Lady Tremaine forbids her to try on the shoe on the grounds that she is Ella's mother, but is overruled by the captain. Ella then curtly tells Lady Tremaine that she is not, and never will be, her mother.
Ella and Kit are finally reunited. Kit recognizes Ella even without the shoe, which fits perfectly. The stepsisters plead for forgiveness. Ella leaves with Kit after forgiving her stepmother, who along with her daughters and the Grand Duke are forever exiled from the kingdom for treason.
At the wedding, Kit and Ella are crowned as the new king and queen. The Fairy Godmother narrates that they become the land's most beloved monarchs, ruling with the courage and kindness that Ella had promised her mother, and they lived happily ever after.