Set several years after the first film, Ariel and Prince Eric are happily married with a daughter, Melody. In order to protect Melody from the Sea Witch, Morgana, they have not told her about her mermaid heritage. Melody is curious and ventures into the sea, where she meets new friends. But will she become a pawn in Morgana's quest to take control of the ocean from King Triton?
| Actor | Role |
|---|---|
 Jodi BensonAriel (voice) | Ariel (voice) |
 Samuel E. WrightSebastian (voice) | Sebastian (voice) |
 Tara StrongMelody (voice) | Melody (voice) |
 Pat CarrollMorgana (voice) | Morgana (voice) |
 Buddy HackettScuttle (voice) | Scuttle (voice) |
 Kenneth MarsKing Triton (voice) | King Triton (voice) |
 Max CasellaTip (voice) | Tip (voice) |
 Stephen FurstDash (voice) | Dash (voice) |
 Rob PaulsenPrince Eric (voice) | Prince Eric (voice) |
 Clancy BrownUndertow (voice) | Undertow (voice) |
 Cam ClarkeFlounder (voice) | Flounder (voice) |
 René AuberjonoisChef Louis (voice) | Chef Louis (voice) |
 Kay E. KuterGrimsby (voice) | Grimsby (voice) |
 Edie McClurgCarlotta (voice) | Carlotta (voice) |
 Tress MacNeilleMother Penguin/Baby Penguin (voice - uncredited) | Mother Penguin/Baby Penguin (voice - uncredited) |
 Frank WelkerMax (voice) | Max (voice) |
 Justin SchulteHandsome Boy (voice) | Handsome Boy (voice) |
 Blake McIver EwingBoy #1 (voice) | Boy #1 (voice) |
| EEmily HartMergirl #1 (voice) | Mergirl #1 (voice) |
 Marcus TojiMerboy #2 (voice) | Merboy #2 (voice) |