25+ Mermaid Halloween Costumes for a Magical, Under-the-Sea Look

There’s just something irresistible about mermaid costumes—they’re glamorous, whimsical, and perfect for adding a splash of fantasy to your Halloween look.

Whether you dream of shimmering sequins, flowing iridescent tails, or seashell crowns fit for an ocean queen, the mermaid aesthetic offers endless ways to get creative.

In this guide, you’ll find 25+ magical mermaid Halloween costume ideas—from classic Ariel-inspired ensembles to edgy, modern takes—that will have you turning heads on land and under the sea.

25+ Mermaid Halloween Costumes

Mermaid Halloween costumes are the perfect blend of elegance, fantasy, and a little bit of mystery. Whether you choose a sparkly, pastel look or a darker, siren-inspired vibe, there’s a style here to match your personality and make a splash at any party.

With the right accessories—think seashell crowns, pearl jewelry, and shimmering makeup—you can transform into the ultimate sea goddess. So dive in, let your creativity flow, and make this Halloween one to remember with a magical under-the-sea look.