A little girl named Fei Fei loved being told the story 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 on the moon. 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 gifts her daughter a bunny named Bungee, before passing away.
Fei Fei, who is intelligent and likes to study space, still believes in Chang’e four years later, and is upset when she learns that her father is engaged to Mrs. Zhong, and is annoyed by her stepbrother-to-be, Chin. Fei Fei’s family joins them for the Moon Festival celebration, and she remembers her mother. Inspired by the legend of Chang’e and seeing a white crane flying upward toward the moon, she decides to build a rocket to the moon to prove to her dad Chang’e is real. She designs a rocket boosted by fireworks resembling a Chinese rabbit-shaped paper lantern that uses a maglev track to boost its 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 beset by playful lion spirits, who then rescue them and take them to Lunaria, a city of radiant light on the moon’s dark half.
They are introduced to Chang’e and her backup dancers, the Lunettes, who are performing a concert for the citizens of Lunaria. 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 to her dad 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 and Houyi can no longer return. 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, causing a meteor shower with her emotions. While Chin is trapped in a chamber by Chang’e, Bungee follows the Jade Rabbit into his workplace and ends up falling in love with him because he accidentally made her ears glow with lasers. Meanwhile, Fei Fei and the Biker Chicks head to her rocket’s crash site, where Fei Fei meets an exiled Lunarian named Gobi. She discovers her Chang’e doll, which she suspects to be the gift, but the Biker Chicks grab 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 he sang to her 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. Afterwards, Chang’e is able to make a full jade circle with a half she already had. Chang’e and Houyi are then briefly reunited, but Houyi explains he cannot stay and begins to fade away as he tells Chang’e to move on. 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 as well 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 new love all around them, for Chang’e in the form of the Lunarians and for Fei Fei in the form of Chin. This allows the two to accept their loved ones’ deaths and effectively move on from them, restoring life 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; she 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 and to watch cranes fly up towards it in the night.