A girl named Fei Fei is being told the legend of the Moon goddess Chang'e who took a potion for immortality, causing her to become a goddess and ascend to the Moon without her lover Houyi, and awaits for him there. In preparation for the annual Moon Festival, Fei Fei and her family make mooncakes for the village. However, Fei Fei's mother falls ill, and gives her daughter a white rabbit named Bungee before passing away.

Fei Fei, who still believes in Chang'e four years later, is upset when she learns that her father is engaged to Ms. Zhong, and is annoyed by her son, Chin. Fei Fei's family joins them for the Moon Festival celebration, and she remembers her mother. Inspired by a crane and the legend of Chang'e, she decides to build a rocket to the Moon to prove that Chang'e is real. She designs a rocket that resembles a Chinese paper lantern in the shape of a rabbit that uses fireworks to boost her speed. Her rocket almost succeeds until she realizes that Chin snuck aboard her rocket and they begin to crash to Earth. Suddenly, the rocket is captured in a mystical beam of energy and taken to the Moon. They crash-land after being "attacked" by 2 friendly foo dogs, who then rescue them and take them to Lunaria.

They are introduced to Chang'e and her backup dancers, the Lunettes. Chang'e tells Fei Fei that she was supposed to deliver a gift for Chang'e to bring Houyi back. Fei Fei takes a photo with Chang'e to prove she is real, but Chang'e takes the photo from Fei Fei and demands the gift. Fei Fei doesn't know what she is talking about, and a frustrated Chang'e announces a competition to find her gift before the last of the moondust falls. Fei Fei gets upset with Chin and leaves him, getting a ride with the Biker Chicks to the crash site. Chin sees some Lunettes with the photo and is captured by Chang'e who demands the location of the gift. Chang'e challenges Chin to a game of ping pong that Chin wins, further upsetting Chang'e. Chang'e cries in despair that she will never see Houyi again. While Chin is trapped in a chamber by Chang'e, Bungee follows the Jade Rabbit into his workplace. Meanwhile, Fei Fei and the Biker Chicks head to her rocket's crash site, where the former meets an exiled Lunarian named Gobi. She discovers her Chang'e doll, which she suspects to be the gift, but the Biker Chicks snatch the doll and leave Fei Fei and Gobi behind.

Fei Fei and Gobi head to Lunaria on the backs of giant toads, where Gobi reveals that Chang'e exiled him due to a song about moving on. Fei Fei and Gobi catch up to the Biker Chicks, but during their scuffle, the doll is destroyed. However, Fei Fei discovers in one of her mooncakes a broken half of an open jade circle and realizes that it is Chang'e's gift. They return to Lunaria's palace, rejoin Chin and Bungee, and present the gift to Chang'e, who makes a full jade circle. Chang'e and Houyi are then briefly reunited, but Houyi tells Chang'e to move on before fading away. Refusing to accept this, Chang'e slips into a state of depression, causing all the light in Lunaria to extinguish.

Fei Fei tries to reach out to Chang'e, but the moment she enters Chang'e's state of sadness, she also becomes depressed due to a vision of her mother. Realizing that they both must move on from their tragedies, Chang'e and Fei Fei encourage each other to find the love all around them. This allows the two to accept their loved ones' deaths, restoring light to Lunaria.

Chang'e thanks Fei Fei and allows her and Chin passage back home—excluding Bungee, who stays on the Moon with Jade Rabbit—and lifts Gobi's banishment. Fei Fei and Chin bid farewell to the Lunarians and return home, where Fei Fei accepts her father and Mrs. Zhong's marriage and Chin as her brother. About a year later, Fei Fei is living happily with her new family and continues to look up at the Moon, watching as cranes fly up towards it in the night.