Athletic Leakproof Bikini

High-performance underwear with an ultra thin, built-in panty liner. Absorbs up to 3 tsp of moisture (approx. 2 tampons), great for light bladder leaks and as back-up period protection.

FYI we also make leak-proof underwear for teens. Click here for Knixteen.

Classic Colors
Questions & Answers

Leakproof Essentials

We went to Italy to find top-of-the-line textiles from world-class cycling. And put them in underwear.
Super Absorbent
Leakproof technology absorbs up to two tampons worth of liquid keeping you leak free.
Quick Dry Gusset
Dries 2-3 times faster than regular cotton and carbon cotton fights odor.
Bonded Construction
No more visible panty lines, and it's washer and dryer safe.
"Best undies ever! Comfortable and do exactly what they say they will!"

– Holly O.

Read More Reviews


Period underwear for teens. Same great leakproof technology, now available in sizes for tweens and teens!

How It Fits

A classic mid rise silhouette with medium coverage through the hip and bum. The stretch tech means these will relax a bit more than the Everyday line.


Body: 77% nylon, 23% LYCRA®
Gusset Liner: 86% cotton, 10% spandex, 4% carbon
Gusset: Fresh Fix Technology®


Machine wash cold with mild detergent, do not bleach, lay flat to dry.

They work great for LBL caused by running and are fantastic on lite period days.
Jennifer S.

Tech To Take

Your Life Back


We're done with uncomfortable underwear. With 4-way stretch fabrics, your Knix move and mold to your shape.


Each Knix product is tested by 1000s of real women to make sure it's ready for your real life.


Moisture-wicking. Anti-odor. Quick-dry. Because we know what it takes to conquer your day.

Athletic Leakproof Bikini Reviews

Q & A


Q: Is there a way to sign up for a waiting list, or some kind of notification when XL is back in stock? Will they be back in stock?


A: Yes! You should have the option to sign up for a Back in Stock notification located under the product page.