Your Bag

Your cart is empty

But you're full of potential..
Rewards Members Earn 0 Points

Suggestions

Top Picks

The Quintessential Sleep Set

$150.00 CAD

Color: Dark Cherry Limited Edition

Super Leakproof® Dream Short

$48.00 CAD

Color: Tapestry Limited Edition

Shimmer Stretch Bralette

$58.00 CAD
10% off Bra & Underwear Sets*

Color: Black

SuperPlus Leakproof® No-Show Bikini

$36.00 CAD
Mix & Match: 3+ for $33 each

Color: Dark Cherry Limited Edition

Home / Swim / Leakproof Classic One Piece Swimsuit
Sale

Leakproof Classic One Piece Swimsuit

$75.00 CAD

$125.00

40% off
Checkmark

Our #1 selling one-piece

Checkmark

Built-in leak protection

Checkmark

Premium UPF 50+ fabric

| Espresso
| Espresso
| Espresso
| Espresso
| Espresso
| General

Absorbency: Light

Light
Drop
Drop
Drop
Drop
Drop
about 1-3 regular tampons
Essential
Drop
Drop
Drop
Drop
Drop
No Absorbency

Color: Espresso Limited Edition

Size:

True to Size

•

Size:

Size and Fit Guide

Free Shipping on orders $100+

Shipping

Shipping
Processing Timelines

Please allow 1-2 business days for our warehouse team to pack and ship your order. During peak periods such as sales, holidays and product launches, please allow up to 4 business days for us to process your order.

Delivery Time

For the most up-to-date delivery time estimates, please refer to the shipping timeline at checkout. Delivery timelines vary depending on location and do not include processing times.

Shipping Charges

Orders over $100* CAD = Free Shipping (2-6 business days)
Orders under $100* CAD = $12 CAD Shipping (1-3 business days)
Orders delivering to NWT, Nunavut and Yukon are subject to $20 delivery fee.
*After discounts, before shipping and taxes.
Easy Returns within 30 Days

Returns

Returns
Free Returns

Knix covers the return shipping fees for exchanges and refunds initiated through our Return & Exchange Portal. Exchange orders initiated through our Return & Exchange portal are also eligible for free shipping within the USA and Canada. Please note, the shipping fees on your original order are non-refundable.

Return Policy

Return policy varies by product, please check if your item is refund or exchange eligible by viewing our full policy here.

Sale & Last Call

Items discounted below 30% are eligible for size exchange or store credit. Items discounted 30% and above are final sale – no refunds, store credits, or exchanges can be accommodated.
Rewards Members Earn 75 Points

"Brilliant for unexpected spotting."

- Oprah Daily

You May Also Like

Leakproof Deep V One Piece Swimsuit

$125.00 CAD

Leakproof UltraThin No-Show High Rise

$32.00 CAD

Revolution V-Neck Bra

$68.00 CAD

Classic Style

A fit we've spent years perfecting.

Stay Sun-Safe

Premium UPF 50+ fabric shields you from UV rays while you relax, swim, and play.

Worry-Free Protection

Discreet, built-in protection that absorbs about 1 regular tampon worth.

Feels Made For You

Thicker, adjustable straps make it adaptable for different sizes and torso lengths. It features a shelf bra with removable cups and full bum coverage.

Zoom

| Espresso
| Espresso
| Espresso
| Espresso
| Espresso
| General

How to Choose?

Essential

Drop
Drop
Drop
Drop
Drop
  • • Everyday Wear
  • • No leakproof protection
  • tsp
    0 tsp

Heavy

Drop
Drop
Drop
Drop
Drop
  • • heavy period days
  • • overnight protection
  • • light bladder leaks
  • tsp
    about 8-14 tsp
  • pad
    about 1.5-3 regular pads
  • tampon
    about 4-7 super tampons
  • cup
    about 1.5-3 menstrual cups

Light

Drop
Drop
Drop
Drop
Drop
  • • light period days
  • • sweat
  • • discharge
  • tsp
    about 1-3 tsp
  • pad
    about 1-3 pantyliners
  • tampon
    about 1-3 regular tampons
  • cup
    about 0.5 menstrual cups

Moderate

Drop
Drop
Drop
Drop
Drop
  • • moderate period days
  • • light bladder leaks
  • • sweat
  • tsp
    about 4-8 tsp
  • pad
    about 1-1.5 regular pads
  • tampon
    about 2-4 super tampons
  • cup
    about 0.5-3 menstrual cups

Ultra

Drop
Drop
Drop
Drop
Drop
  • • extra heavy period days
  • • overnight protection
  • • light bladder leaks
  • tsp
    about 15-20 tsp
  • pad
    about 1.5-2.5 super pads
  • tampon
    about 7-11 super tampons
  • cup
    about 2-3 menstrual cups
LEAKPROOF SWIM WORKS IN LAYERS

Built-in protection that feels like nothing at all.

Just like regular swimwear—but better! Non-swelling liner and patented no-show design.

Soft Top Layer

Top Layer

Smooth and comfortable liner in swimsuit fabric.

Holiday Top Picks

Shop All Arrow Right

Leakproof UltraThin No-Show Bikini Shimmer 3-Pack

$75.00 CAD

Color: Tapestry/Burnished Gold/Dark Cherry Limited Edition

WingWoman Contour Bra

$75.00 CAD
10% off Bra & Underwear Sets*

Color: Tapestry Limited Edition

The Quintessential Sleep Set

$150.00 CAD

Color: Ivory Limited Edition

Light Leakproof UltraThin No-Show Thong

$27.00 CAD
Mix & Match: 3+ for $20 each

Color: Warm Sand

Shimmer Stretch Bralette

$58.00 CAD
10% off Bra & Underwear Sets*

Color: Black

Overnight Favorites Gift Set

From 
$83.00 CAD

SculptRib™ Cotton Long Sleeve Top

$62.00 CAD

Color: Dark Cherry Limited Edition

Modal Rib Henley Sleep Set

$75.00 CAD

Color: Black

4.6
Rated 4.6 out of 5 stars
Based on 186 reviews
Total 5 star reviews: 151 Total 4 star reviews: 14 Total 3 star reviews: 12 Total 2 star reviews: 3 Total 1 star reviews: 6
91%would recommend these products
ComfortRated 4.8 on a scale of 1 to 5
FitRated 0.0 on a scale of minus 2 to 2
SupportRated 4.5 on a scale of 1 to 5
EffectivenessRated 4.6 on a scale of 1 to 5
Ease of UseRated 4.7 on a scale of 1 to 5
Write a Review (Opens in a new window)
186 reviews
  • Rated 5 out of 5 stars
    1 week ago
    classic one piece swimsuit

    This swimsuit is so comfortable and nice to have on for a lot of the day.

    Erika H.
    Verified Buyer
    Was this helpful?
  • Rated 5 out of 5 stars
    1 month ago
    Perfect for t’allais people

    Long Torso fits perfectly.

    Marie-France F.
    Verified Buyer
    Was this helpful?
  • Rated 5 out of 5 stars
    1 month ago
    I love it!

    Super comfortable and long enough in the torso for me. I love it!

    Dixie-Anne G.
    Verified Buyer
    Was this helpful?
  • Rated 5 out of 5 stars
    2 months ago
    Favourite bathing suit!

    Love this suit so much, only feedback is that I wish they made the long torso in more colours!

    Rebecca M.
    Verified Buyer
    Was this helpful?
  • Rated 5 out of 5 stars
    2 months ago
    Perfect fit!

    This swimsuit is perfect. I really recommend it for women who have bigger bellies (like me). The extra length allows for everything to fit inside the suit nicely. I buy one once a year. I just wish you had nicer and brighter colours and prints like for the other swimsuits. I would buy at least 2 per season.

    Karine
    Verified Buyer
    Was this helpful?
  • Rated 5 out of 5 stars
    2 months ago
    The fit

    Great fit.. covers bum well, I like the feel of the suit

    Janet M. S.
    Verified Buyer
    Was this helpful?
  • Rated 5 out of 5 stars
    2 months ago
    Classic one piece swimsuit

    This is the best bathing suit I have ever bought.

    Darlene R.
    Verified Buyer
    Was this helpful?
  • Rated 5 out of 5 stars
    2 months ago
    It very comfortably

    It was much better than I can go swimming

    Mckenzie F.
    Verified Buyer
    Was this helpful?
  • Rated 3 out of 5 stars
    2 months ago
    3 Stars

    The fabric itself is quite good really comfortable but one thing i want to point out is the straps are sewn on quite badly there are loose strings and the width of the straps are very thin for ppl with broader shoulders not recommended. Also i wish they made the straps wider. Without the loose strings. The sewing is not great

    jessica
    Was this helpful?
  • Rated 5 out of 5 stars
    2 months ago
    Knix swimsuit

    Great fit and top quality. I will start shopping at Knix going forward for many of my lingerie and sport needs.

    Sharon R.
    Verified Buyer
    Was this helpful?
  • Rated 5 out of 5 stars
    2 months ago
    Great Purchase

    Great, fit. Nice quality

    Holly S.
    Verified Buyer
    Was this helpful?
  • Rated 5 out of 5 stars
    2 months ago
    Very comfortable.

    I bought this bathing suit in 3 different colours.

    Very comfortable style with great coverage.

    Maty Y.
    Verified Buyer
    Was this helpful?