Mulan is the only child of Fa Zhou, a former war veteran, and Fa Li. Mulan was forced to go to the town Matchmaker to find her a husband, which ends in humiliating failure. Shortly after, the Chinese Emperor's counselor, Chi-Fu, arrives in her village to announce that the deadly Huns, led by Shan Yu, have invaded China and that one man in every family must serve in the war. Despite her protests, her father says that he will go in spite of his old age and old war wounds. Mulan decides to go in his place posing as a man, cutting her long hair with a sword, stealing her father's armor and riding away on her horse, Khan, so she will keep him from risking his life.
On her way to the army camp, Mulan meets Mushu, a small dragon who claims to be a guardian sent by her ancestors. He agrees to help her pass as a soldier. Though Mulan fails the army training at first, she uses her intelligence and becomes the first soldier to solve a puzzle set by Li Shang, her unit's commanding officer.
Afterward, she rapidly progresses to become one of the best soldiers in the unit. She also befriends Yao, Ling, and Chien Po, three fellow soldiers, though she is forced to hide her gender. Through the machinations of Mushu, the soldiers are called to the war front.
After finding that the Chinese Army, led by Shang's father General Li, has been completely destroyed by the Huns, Shang leads Mulan and the other soldiers to stop them. Despite the unit being outnumbered, Mulan is able to defeat the Huns by starting an avalanche and burying them by way of the last rocket in the army. She sustains an injury from Shan-Yu, which results in her true gender is revealed. She is spared death, the punishment for a woman joining the army, as Shang's way of repaying the debt from Mulan rescuing him during the previous battle.
Mulan is left behind by the army and prepares to return home. However, she discovers that Shan-Yu and his five generals have survived and are heading towards the Imperial City. Mulan attempts to warn Shang, but she is ignored because she is a woman. However, when Shan Yu captures the Emperor, Shang, Yao, Ling, and Chien Po join her in a rescue attempt. Mulan disguises herself, Yao, Ling, and Chien Po as concubines and takes out the Hun guards, allowing Shang to reach Shan Yu and the emperor. Yao, Ling and Chein Po escape with the Emperor, but Mulan remains behind after Shang is knocked unconscious by Shan Yu.
She reveals herself to the ruthless leader of the Huns as the soldier who took down most of his army, which angers Shan Yu. Shan Yu draws his sword and angrily slashes at her, tearing down portions of the castle in the process. While running from Shan Yu, she comes up with a plan to kill him by means of fireworks. While Mushu goes to get the fireworks, Mulan faces Shan Yu on the roof of the Emperor's palace. She disarms him with a paper fan and uses his sword to pin him to the roof, allowing Mushu to fire fireworks at Shan Yu, presumably killing him. Mulan is oppressed by Chi Fu for the final time when he arrogantly says that as a woman, she is unworthy of being called a hero or being worth anything.
Mulan is then confronted by the Emperor with her various crimes, having heard about them from Chi Fu. At the same time, he acknowledges that she saved all of China and bows to her out of respect. His gesture results in all the gathered people bowing as well. The Emperor first offers Mulan a council position than a job as consul, both of which Mulan refuses. The Emperor instead gifts her with his personal crest and Shan Yu's sword. Mulan returns home and is able to reconcile with her father. The end of the film shows Mulan inviting Shang, who had followed Mulan under the guise of returning her helmet, to dinner.
- She appears attending the coronation of Ben standing near her husband and Lonnie.
- She was voiced by Ming-Na Wen in her debut, Mulan.
- She is the third Disney Princess to not be white. The first was Jasmine, the second was Pocahontas, and the fourth was Tiana.
- In Rise of the Isle of the Lost, it's revealed that she has a son and that he is actually older than Lonnie.