One of the Princesses of Heart, her world was destroyed by Maleficent. She was taken and held deep within Hollow Bastion until all seven Princesses were collected. She and the other princesses upgraded Sora's Fire spell to Firaga. She first appeared in Hollow Bastion in Kingdom Hearts.
When Kingdom Hearts was sealed she was returned to her own world.
Kingdom Hearts
Cinderella was a lovely girl who had to work as a servant in her own house because of her wicked stepmother and two ugly stepsisters. When the prince's ball was heard of, Cinderella tried to finish her work in order to go. Her mice friends made her a dress so she could go to the ball. But her stepsisters ruined it. Her Fairy Godmother soon came and gave Cinderella a lovely dress with glass slippers and warned to be home at midnight. At the ball, she and the prince danced and fell in love. It is unknown at what time she was taken by the heartless to Hollow Bastion.
Birth By Sleep
Cinderella is set to appear in the upcoming PSP game Kingdom Hearts: Birth by Sleep.