How To: DIY All Black Evil Mermaid Costume For Halloween

What little girl doesn’t dream of dressing up in a mermaid costume for Halloween? I used to beg for a mermaid costume every year, I was obsessed with Ariel from The Little Mermaid. But never got one.This year, I took matters into my own hands and decided to make my own costume to fulfill my childhood dreams. Since my aesthetic has changed significantly over the years, I opted to go a more… gothic route. I wanted something dark and chic. So this year, I whipped up a DIY Evil Mermaid Costume!

DIY Evil Mermaid Costume for Halloween

If you follow me on Instagram you might have seen me hinting at some really fun DIY halloween costumes and decorations.

You know I love edgy Halloween decor. So taking Ariel to the dark side and making her more of a siren is totally on brand for me.

In Greek mythology, sirens were described as beautiful women, half-bird half-women, and as mermaids, luring men to their deaths with some sexy singing.

For my costume, I was going for a Morticia Addams, Hook mermaid vibe. Two of my favorite movies as a kid were the Addams Family & Hook, primarily because of the mega babes and awesome costumes.

This DIY is relatively easy and inexpensive. You’ll need to set aside a few hours for putting it together and letting it dry before wearing it. If a goth mermaid isn’t your vibe, you can go with any other color combination! There are so many mermaid costumes you can choose from online, but it’s so much more fun and unique when you make it yourself.

Here’s a step by step tutorial for putting together your own costume.

DIY Supplies

DIY Black Mermaid Top

How to make a mermaid costume top and crown for halloween

The first thing I did was spray paint my shells black. I set out some old cardboard boxes on our grass. I recommend doing this outside and in an area you’re not worried about potentially over spraying. I used a black spray paint that has a primer mixed in. There are instructions on the back of the can, but just remember to hold the paint about a foot away from the shells. I painted the scalloped seashells, mixed seashells, some starfish, some fun starfish hair clips & my crown.
After your pieces have dried, you have the option of doing a very light layer of silver spray paint on top. I did a very small mist on half of the shells, just to give it more dimension.
Once they’ve dried completely, lay your bustier or bra on a flat surface and arrange the seashells to your liking. I opted for a bustier style top because I wanted a little more coverage. If you want to have your midriff showing, you can choose a strapless bra. Be sure to set an assortment of shells aside for your crown.
Use your hot glue gun to secure all of the seashells onto the bra. Make sure all of the shells are intact and add more glue if needed. I took the barrette backing off of a few of the hair clips and added them to the bodice as well.
Once the glue is dry, take your entire top outside and place it on cardboard. I recommend spraying it with clear acrylic sealer, aka Mod Podge. That way none of the shells will fall off. It helps solidify the top so that when you move, the shells won’t pop off.

DIY Evil Mermaid Tiara

Your mermaid costume tiara should already be spray painted black. You can use a tiara or a headband, depending on the style you prefer. I went with a tiara because I wanted it to be a little larger and more noticeable. You won’t be able to lay the shells out, so take a few minutes to place the shells and get an idea of how you want them arranged and overlapped.
Follow the same process as above, using your hot glue gun to attach the various shells to your headpiece.
Once it’s dry, take it outside and spray with Mod Podge.

Black Mermaid Skirt

There aren’t any instructions here! Just find a mermaid tail that fits! I bought my skirt on Amazon. I picked a faux leather mermaid skirt and am obsessed with how it looks in person. I recommend sizing up, they’re fairly tight and if you get one that’s too small, it will make it hard to walk. There are a ton of other fun color options too if you’re going for a different color scheme mermaid.