Thumbelina is a small girl of about fifteen with strawberry blonde hair and blue eyes. She is kindhearted and is extremely romantic. She can easily be brought down by the world but is known for having good friends to keep her afloat.
A lonely widowed old woman is given a seed by a good witch. Once planted, the seed grows into a flower, and a tiny girl emerges from inside the blossom, no bigger than the old woman's thumb. The old woman names the tiny girl Thumbelina and raises her as her own.
Although Thumbelina loves her mother, she craves companionship to find someone her own size. One night, the fairy prince Cornelius stumbles upon Thumbelina after hearing her beautiful singing. The two take a ride on Cornelius' bumblebee, and fall in love; during this ride Mrs. Toad and her son Grundel are enchanted by Thumbelina's singing. Cornelius promises to return the next day, but that night, Mrs. Toad kidnaps Thumbelina from her bed and takes her away to her show boat, where she desires Thumbelina to join their troupe and marry Grundel, who is in love with her. They leave Thumbelina alone on a lily pad to fetch a priest; she is rescued by a friendly swallow, Jacquimo. Jacquimo's friends, the jitterbugs, promise to help Thumbelina get home safely while Jacquimo sets off to find Cornelius. Meanwhile, Cornelius learns of Thumbelina's kidnapping and ventures out to find her.
While trying to get home, Thumbelina is ambushed by Berkeley Beetle, who scares the jitterbugs away. He too becomes enamored with her singing and promises to show her the way home if she sings at his Beetle Ball first. She reluctantly complies, but her bug disguise falls off during the concert and she is denounced as ugly. Beetle throws her out without helping her. Jacquimo appears and promises that he will find Cornelius and bring him to Thumbelina, but winter arrives and Jacquimo impales his wing on a thorn and is knocked out by the cold while Cornelius falls into a lake and ends up frozen in the ice.
Thumbelina is later found by Miss Fieldmouse and taken to her underground home for shelter. She tells her of Cornelius' fate, leaving her devastated. She later meets Miss Fieldmouse's neighbor, Mr. Mole, who leads her to Jacquimo's body, though Thumbelina realizes he is alive. Mr. Mole expresses a desire to marry Thumbelina, and she reluctantly accepts after persuasion from Miss Fieldmouse. Jacquimo, however, recovers and leaves to find Cornelius, refusing to believe he is dead.
Grundel ventures out to find Thumbelina and finds Beetle, who he coerces into helping him by removing his wings to ensure his cooperation. Beetle finds Cornelius and brings him to Grundel, also informing him of Thumbelina's wedding to Mr. Mole. They head for Mr Mole's home to retrieve Thumbelina, while the jitterbugs find and thaw Cornelius' body out. At the wedding, Thumbelina finds herself unable to marry Mr. Mole. Grundel and Beetle appear and a chase ensues. Cornelius appears and confronts Grundel; the ensuing fight sends them both falling into an abyss. Thumbelina escapes and is reunited with Jacquimo, who takes her to Cornelius' kingdom, the Vale of the Fairies, and has her sing in order to lure Cornelius out. He appears, having survived the fall, and proposes to her; Thumbelina accepts and magically grows her own pair of wings.
With Jacquimo, Thumbelina's mother and the fairy court in attendance, Thumbelina and Cornelius are married and depart on Cornelius' bumblebee living happily ever after. Images shown during the credits reveal that Beetle resumed his singing career and grew new wings; Miss Fieldmouse married Mr. Mole; Grundel survived the fall with minor injuries and fell in love with a female toad; and Mrs. Rabbit and Mr. Fox settled their differences and found friendship.
Thumbelina is voiced by Jodi Benson, who is best known for voicing Ariel from Disney's The Little Mermaid franchise.
Coincidentally, both movies, The Little Mermaid (1989) and Thumbelina (1994) are based off fairy tales written by Hans Christian Anderson.