Ariel meets Sora, Donald, and Goofy when she is running away from Heartless with Sebastian and Flounder. She helps Sebastian and Flounder teach Sora how to move around in the water, but the lesson is interrupted by more Heartless. Ariel asks for the trio to help them reach the palace. Upon arriving, Triton forbids her from leaving the palace. Ariel decides to help the three find Atlantica's keyhole after hearing Goofy mention it to her father. They journey to the Sunken Ship where she finds a crystal that resembles her father's trident, which has the power to reveal the Keyhole. King Triton arrives in time to destroy it, and leaves Ariel in tears.
The sea witch, Ursula, lures Ariel into helping her steal the Trident from King Triton, with the promise of helping Ariel get to other worlds, while also revealing that Sora, Donald, and Goofy are in fact from another world. However, things don't go as Ariel planned, as Ursula makes off with the trident and injures Triton. With Ariel's help, Sora, Donald and Goofy defeat Ursula.
After sealing the Keyhole, Sora apologizes to Ariel for lying to her, but she lets it slide, confident that, if they could find a way to travel to different worlds, then so can she.
Ariel later appears as a memory of Sora, on Atlantica's floor in Castle Oblivion. She is first seen swimming towards Sora, Donald, and Goofy. She quickly informs them not to tell anyone that they saw her and swims off. Afterwards, Sora and company find out she was running away because she stole her father's Trident to save Flounder from Ursula's clutches. Sora and his friends help Ariel confront Ursula and save Flounder. After Ursula's defeat Sebastian arrives and Ariel decides to face the consequences for taking the Trident.
A year later, Ariel saves Prince Eric from drowning and takes him to shore. There she sings to him until he awakes, fleeing back underwater once his eyes open.
Unable to forget about the prince, she falls into deep depression, and so Sora and the others decide to help her. When her father finds out that she has fallen in love with a human, he tries to make her forget about him by destroying the statue of him that Flounder gave to her as a gift to cheer her up. But then Ursula reappears and makes a deal with her: to make her human for three days in exchange for her voice. In addition, she must make the prince kiss her willingly before sunset on the third day, otherwise she will become hers forever. Despite the hardship, she signs the contract and finally gets to meet Eric in person, although he does not recognize her at first.
On the third day, Ariel gets her voice back with Sora's help, and they all battle the sea witch again. Once Ursula is defeated, Ariel reveals to Eric that she is a mermaid and says goodbye to him, but he does not change his feelings about her. Seeing how much they are in love, King Triton's view of humans changes and he lets his daughter be with a human prince. Later, Ariel is disappointed to learn that Sora, Donald, and Goofy are leaving, but they refuse to say goodbye and assure her in song that they will meet again, to which she happily agrees.
Ariel later returns to her human form, and marries Prince Eric.
Ariel is a bright, spirited mermaid that thinks and acts for herself and doesn't do what others tell her what to do. She can act rebellious at times and act rashly to get what she wants, which lands her in trouble. She doesn't wait for things to happen to her and is strong-willed and proactive about her future. She has a big sense of adventure, always wanting to find something new even if it is dangerous. She also has feelings of disenchantment and longing when she longs for a new world, be it either the human world above or a new one altogether. But she can also be somewhat gullible, twice falling for Ursula's manipulative skills, even in Kingdom Hearts II, which occurs after Ariel finds out of Ursula's deceptive and antagonistic nature. She is also protective of her friends, doing anything for their safety, as seen when she stole the Trident in Kingdom Hearts: Chain of Memories.
Ariel is a slender mermaid with very thin wrists and hourglass figure waist. She has a green tail with paler green, translucent fins and wears a brassiere made out of purple sea shells. She has bright blue eyes and full red lips. Her most defining feature is her long, bright red hair that altogether is almost bigger than her entire body.
In Kingdom Hearts II, she is turned into a human for a short time with long slender legs. She is shown in an old sail with some rope keeping it closed when she is first changed into a human. After being taken in by Prince Eric, she wears a dress with light blue sleeves, a black bodice, and blue skirt. She also wears a big blue bow in her hair and black heels.
 Kingdom Hearts
Ariel is only a party member in Kingdom Hearts. Ariel cannot equip a weapon and attacks using her tail. She thus has very low attack power, and instead fights using magic. Therefore, her abilities are geared towards increasing her magical abilities, and she has high MP. Ariel has three equipment slots and five item slots. Her abilities are as follows:
 Kingdom Hearts Re:Chain of Memories
Ariel is a friend card that appears in Kingdom Hearts: Chain of Memories and Kingdom Hearts Re:Chain of Memories. When used, Ariel is called into the battle. She swims in circles around the battle field, striking enemies caught in her way. She joins Sora's party as a friend card when Sora talks to her and offers his help.
Spiral Wave is Ariel's sleight where she rushes into the enemy twice to three times, finishing off with a tail fin kick. In Kingdom Hearts: Chain of Memories, nothing is required of the player besides stocking her cards and using them. In Kingdom Hearts Re:Chain of Memories, the player must press when it flashes on-screen to add an attack. Pressing when it isn't on-screen will cancel the sleight. It can be used with two or three Ariel cards.
Ariel first appeared in Disney's 1989 movie The Little Mermaid where she is the main protagonist of the film. Ariel was the seventh daughter of King Triton, ruler of Atlantica, after her six older sisters, Aquata, Andrina, Arista, Attina, Adella and Alana. Ariel always dreamt about the world above the sea (the human world) and is differentiated from her sisters due to her curious and rebellious nature while also possessing a distinct and lovely singing voice. She is first seen looking for things from the human world in a sunken ship.
 See also