Sophie, a hatter, is a responsible-yet-plain 18-year-old girl who goes to the bakery to visit her sister when she encounters by chance a mysterious wizard named Howl. This encounter arouses the evil Witch of the Waste, who later enters the hat shop and transforms Sophie into a 90-year-old woman. As the curse prevents her from telling anyone of her condition, Sophie decides to leave and seek out a cure.
Along the way, Sophie meets upon the hill a scarecrow (whom she names Turnip-Head). She passes the mysterious Moving Castle and enters it. At this point, she meets an enchanted fire demon named Calcifer, who powers the castle and recognizes that Sophie has been cursed. Calcifer offers to break the curse in exchange for Sophie's help in breaking the spell he's under, which keeps Calcifer bound to the house. When Howl appears, Sophie announces that she is the castle's new cleaning lady, hired by Calcifer because he was sick of how dirty the castle was.
Meanwhile Sophie's home country, the beginning of a war has sparked against another neighbouring town - following the disappearance of the other realm's Crown Prince. Slowly the war begins to creep into Sophie's country itself. Howl receives summons from the King, who orders his various assumed identities to fight in the war. However, Howl comes up with an idea to send Sophie to pose as his mother, announcing what a coward he is and that he would be useless. At the palace, Sophie runs into a asthmatic dog, Heen, who she thinks is Howl undercover. She also meets the Witch of the Waste. They begin to race up the stairs. Once they are inside the castle, the Witch of The Waste finds herself a place to sit down - only to find her magical powers drained by Madame Suliman as a punishment. This causes her to regress into a harmless old woman with little memories of her past actions. Suliman tells Sophie that Howl will meet the same fate if he does not contribute to the war. As Sophie vehemently protests these measures, the Witch's spell temporarily weakens due to the love in her words. This causes Sophie to change briefly to her younger self, then regress back to her older persona. Madame Suliman realizes Sophie's true relation to Howl and her romantic feelings towards him. Howl then arrives to rescue Sophie, Suliman tries to entrap Howl, but with Sophie's help, they manage to escape.
Sophie learns that Howl is able to transform himself into a bird-like creature to interfere in the war, but each transformation makes it more difficult for him to return to human form. Sophie fears that Howl is preparing to leave them, as his remaining time as a human is limited, he returns to interfering in the war. Sophie's mother shows up and is actually under Suliman's control and leaves behind a bag containing a "peeping bug" under her orders. The former Witch of the Waste discovers it and promptly destroys the bug by tossing it into Calcifer. Unfortunately, Calcifer gets sick after eating the bug, rendering him unable to protect the castle from being discovered.
A few hours later, the city is carpet-bombed by enemy aircraft while Suliman's henchmen invade the hat shop. After arriving just in time to protect the hat shop from the bombing, Howl draws the guards away just after healing Calcifer. He tells Sophie he is not going to run away anymore because he has something he wants to protect before leaving to interfere with the war. Deducing that Howl must be saved, Sophie moves everyone out of the castle and removes Calcifer from the fireplace, destroying the castle. She offers Calcifer some of her braided hair to give him strength enough to power a portion of the castle. They head toward Howl when the former Witch of the Waste discovers Howl's heart within Calcifer. Sophie pours water on Calcifer to make her let go of the heart, making Calcifer lose his power. The segment of the castle is split, and she and Heen fall down a chasm.
Making her way toward Howl's heart, Sophie enters through the door into the black region, Howl's childhood. She sees a recollection of how Howl and Calcifer meet: Howl eats Calcifer, who then gains his heart. Sophie finds Howl, having now lost his human consciousness in bird form. They head back to the group, and Sophie asks the Witch for Howl's heart. She gives it to her and places the heart back in Howl, resurrecting him and freeing Calcifer. She kisses the scarecrow who reveals that he is actually the missing prince. Heen shows the scene of their happy end to Suliman, and the war is finally over. Howl, Sophie, and the others are seen high above the bomber planes returning home from the end of the war.
- Sophie as Chieko Baisho in Japanese Version and Emily Mortimer in English Version
- Howl as Takuya Kimura in Japanese Version and Christian Bale in English Version
- Markl as Ryunosuke Kamiki in Japanese Version and Josh Hutcherson in English Version
- Witch of the Waste as Akihiro Miwa in Japanese Version and Lauren Bacall in English Version
- Calcifer as Tatsuya Gashuin in Japanese Version and Billy Crystal in English Version
- 20 November 2004 - Movie theater on Japan
- 20 April 2005 - VHS/DVD release
- 10 June 2005 - Movie theater on USA
- Autumn 2005 - DVD release on USA
- Summer 2011 - DVD release Japan
- 2013 - Blu-Ray release