Sora and his friends meet her in human form at Eric's castle. She is trying to keep her daughter from going out to sea after an encounter with Morgana, Ursula's sister. Somehow, Melody ignored the warnings and had become a mermaid thanks to Morgana. Sora and Ariel begin their search as merpeople also, while fighting off merbandits, deadly sea life and even Undertow. Morgana tries to waylay the heroes with a phantom version of Ursula. Ariel feared that Ursula would be brought back to life, but Sora knew it was but an illusion. Eventually, the heroes encounter Morgana with Melody. After Melody surrenders Triton's trident to Morgana, the sea witch kidnaps Ariel and impriosns Melody in an ice prison. While Ariel breaks herself free, Dash and Tip free Melody. The battle with Morgana's heartless and sea minions begins. When Ariel, Eric, Triton and others are forced to bow to Morgana due to her trident, Sora and Melody resist and take the trident back. After the battle, Sora throws the trident to Triton and he freezes Morgana to death in a block of ice. With the dust cleared, Ariel and Melody share a happy reunion and Sora shakes Ariel's hand for all her help.
In the credits, Ariel is among the people celebrating the merpeople and human reunion.