How To | Toddler Mermaid Costume

Toddler Mermaid Costume, DIY Mermaid Costume, Halloween Costume

Can you tell she is posing and saying “cheese” for all of you. It is tricky to get a picture of her because she pauses for about a half second before she runs up to the camera and tries to see herself in the display on the back. So, she wanted to be a mermaid for Halloween. How did I know that this 21 month old spitfire wanted to be a mermaid? Because she can talk loudly, forcefully and in long sentences already. She loves all things mermaid and of course wants to have a mermaid costume. Who wouldn’t, look how it sparkles, and as she says, “it is prip-pee” (that’s pretty in adult speak).

Halloween Costume, Mermaid Costume

I figured a toddler isn’t going to be able to walk around in a mermaid style skirt and decided a pair of pants would work out better. I thought an added tutu would make it even prip-pee-er and then I found this cute pink swimsuit on clearance for $3 dollars. (If you think you might want to make a mermaid costume and use a swimsuit as a top head online right now, a lot of stores (Target) have swimsuits on clearance.)


  • Mermaid Style Fabric
  • 2 Sheets of Craft Felt
  • Sewing Machine
  • Scissors
  • Thread
  • Pants Pattern

How To:

I want to first tell you about the fabric I used. I found this glittery, sequin like fabric in the clearance bin at Jo-Anns. What I didn’t realize is those shiny dots are actually stuck onto the fabric. While I was sewing, if my needle went through those dots it got sticky goo on the needle and then after awhile the needle would get so sticky the thread would get stuck on the needle and break. So I would actually recommend finding another fabric you like. I have since been back and found a fabric in their Halloween seasonal that looks like a mermaid fin and has a metallic sheen to it. You might want to consider it as an option, unless you have a ton of patience.

Lets start with the fin. Use a piece of 9×11 craft felt and draw an outline on it of your fin shape. Cut out two identical fin shapes to use on each leg of your mermaid pants.

Next the pants. I can’t actually share the pattern with you I used for the pants. But here is one that is really close (Pants Pattern Tutorial). Follow the instructions and sew the pants according to the directions. If your pattern does not have a seam on the outside of the leg, mine did not and either does the link above, then lay your pants out flat and cut a slit the height of your fin up the outer side of each pant leg. With your pants inside out, pin the fin in place so it is inside the pant leg, between the two right sides. Sew along the edge of the pants to secure the fin in place.

How about the tutu? I actually found this tutu with an outfit on clearance for $3 and decided to go with it instead of sewing one myself. If you want to create your own no sew tutu, check out this link: No Sew Tutu. It is really simple.

Now you made a really easy mermaid costume for your toddler and now she can be oh so prip-pee too!



  1. awesome i was google for top ideas, im making my daughter a mermaid for halloween, also with leggings, with so much neg feed back good to know its nt just me

  2. This is EXACTLY what I had in mind for making merman pants for my son, all laid out easy for me! My daughter is going to be Ariel and has a gorgeous dress that my mom made for her, and my son (21 months, 22 by Halloween) wants to be a “mer-mad” (mermaid) like his sister. Now if only I can manage to find a tan long sleeve onesie or shirt…I’ll dye a white one if I have to, but not having to would be easier!

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