THE ULTIMATE UNDERSHIRT  

Stop 100% of Sweat Stains with Numi's Patented Technology

Stay cool, dry, and fresh this summer with our innovative sweat-proof undershirts. 

20% OFF

Use code NOSWEAT at checkout

A person with long dark hair poses with one arm raised, wearing The Signature Undershirt by Numi in light beige, and looking off to the side.
A woman with long dark hair stands facing forward, wearing a light beige short-sleeve top and light brown pants against a plain background. Her Signature Undershirt by Numi ensures she stays comfortable even in the heat, thanks to its sweat-proof design.
A person with long, dark hair is shown from the back wearing The Signature Undershirt in light pink and matching bottoms from Numi against a plain background.
A woman wearing The Signature Undershirt from Numi, a gray fitted t-shirt featuring a hip length, sweat-proof material, reversible neckline, short seamless sleeves with a raw edge, and a slim fit ideal for layering.
Image split in half: the left side features a close-up of The Signature Undershirt's beige sweat-proof underarm shield by Numi in action, while the right side shows a model wearing a beige top. Text highlights product benefits like effective sweat protection, exceptional comfort, and versatile heat-friendly layering options.
Close-up of The Signature Undershirt by Numi in beige, with text detailing features: sweat-proof, all-day comfort, lightweight, 4-way stretch, thermo-regulating material to manage heat, and a durable design to prevent shrinking and fading.
Comparison chart showing Numi's The Signature Undershirt vs. Other T-Shirts. The Signature Undershirt by Numi features built-in underarm shields to stop sweat stains and odors, provides comfortable invisible shields, has seamless sleeves, and is made from breathable fabric.
A person with long dark hair poses with one arm raised, wearing The Signature Undershirt by Numi in light beige, and looking off to the side.
A woman with long dark hair stands facing forward, wearing a light beige short-sleeve top and light brown pants against a plain background. Her Signature Undershirt by Numi ensures she stays comfortable even in the heat, thanks to its sweat-proof design.
A person with long, dark hair is shown from the back wearing The Signature Undershirt in light pink and matching bottoms from Numi against a plain background.
A woman wearing The Signature Undershirt from Numi, a gray fitted t-shirt featuring a hip length, sweat-proof material, reversible neckline, short seamless sleeves with a raw edge, and a slim fit ideal for layering.
Image split in half: the left side features a close-up of The Signature Undershirt's beige sweat-proof underarm shield by Numi in action, while the right side shows a model wearing a beige top. Text highlights product benefits like effective sweat protection, exceptional comfort, and versatile heat-friendly layering options.
Close-up of The Signature Undershirt by Numi in beige, with text detailing features: sweat-proof, all-day comfort, lightweight, 4-way stretch, thermo-regulating material to manage heat, and a durable design to prevent shrinking and fading.
Comparison chart showing Numi's The Signature Undershirt vs. Other T-Shirts. The Signature Undershirt by Numi features built-in underarm shields to stop sweat stains and odors, provides comfortable invisible shields, has seamless sleeves, and is made from breathable fabric.

#1 Best Seller

The Signature Undershirt

$70.00

Use code: NOSWEAT for 20% off at checkout

$52 $65

Elevate Your Outfit: Say Hello to the Better Base Layer

Meet our #1 best seller, The Signature. This OG undershirt is the ultimate base-layer for every outfit. No more sweat-stains or deodorant marks – stay fresh and feel clean all day with this game-changer. With 250,000+ sold worldwide, The Signature Undershirt is the real deal.

*Based on moderate to heavy sweaters

Color

✓ Free Shipping on orders $100+
✓ 30-Day Money Back Guarantee

Styles for Summer Heat

A person with long dark hair poses with one arm raised, wearing The Signature Undershirt by Numi in light beige, and looking off to the side.
A woman with long dark hair stands facing forward, wearing a light beige short-sleeve top and light brown pants against a plain background. Her Signature Undershirt by Numi ensures she stays comfortable even in the heat, thanks to its sweat-proof design.
A person with long, dark hair is shown from the back wearing The Signature Undershirt in light pink and matching bottoms from Numi against a plain background.
A woman wearing The Signature Undershirt from Numi, a gray fitted t-shirt featuring a hip length, sweat-proof material, reversible neckline, short seamless sleeves with a raw edge, and a slim fit ideal for layering.
Image split in half: the left side features a close-up of The Signature Undershirt's beige sweat-proof underarm shield by Numi in action, while the right side shows a model wearing a beige top. Text highlights product benefits like effective sweat protection, exceptional comfort, and versatile heat-friendly layering options.
Close-up of The Signature Undershirt by Numi in beige, with text detailing features: sweat-proof, all-day comfort, lightweight, 4-way stretch, thermo-regulating material to manage heat, and a durable design to prevent shrinking and fading.
Comparison chart showing Numi's The Signature Undershirt vs. Other T-Shirts. The Signature Undershirt by Numi features built-in underarm shields to stop sweat stains and odors, provides comfortable invisible shields, has seamless sleeves, and is made from breathable fabric.
A person with long dark hair poses with one arm raised, wearing The Signature Undershirt by Numi in light beige, and looking off to the side.
A woman with long dark hair stands facing forward, wearing a light beige short-sleeve top and light brown pants against a plain background. Her Signature Undershirt by Numi ensures she stays comfortable even in the heat, thanks to its sweat-proof design.
A person with long, dark hair is shown from the back wearing The Signature Undershirt in light pink and matching bottoms from Numi against a plain background.
A woman wearing The Signature Undershirt from Numi, a gray fitted t-shirt featuring a hip length, sweat-proof material, reversible neckline, short seamless sleeves with a raw edge, and a slim fit ideal for layering.
Image split in half: the left side features a close-up of The Signature Undershirt's beige sweat-proof underarm shield by Numi in action, while the right side shows a model wearing a beige top. Text highlights product benefits like effective sweat protection, exceptional comfort, and versatile heat-friendly layering options.
Close-up of The Signature Undershirt by Numi in beige, with text detailing features: sweat-proof, all-day comfort, lightweight, 4-way stretch, thermo-regulating material to manage heat, and a durable design to prevent shrinking and fading.
Comparison chart showing Numi's The Signature Undershirt vs. Other T-Shirts. The Signature Undershirt by Numi features built-in underarm shields to stop sweat stains and odors, provides comfortable invisible shields, has seamless sleeves, and is made from breathable fabric.
A person with long dark hair poses with one arm raised, wearing The Signature Undershirt by Numi in light beige, and looking off to the side.
A woman with long dark hair stands facing forward, wearing a light beige short-sleeve top and light brown pants against a plain background. Her Signature Undershirt by Numi ensures she stays comfortable even in the heat, thanks to its sweat-proof design.
A person with long, dark hair is shown from the back wearing The Signature Undershirt in light pink and matching bottoms from Numi against a plain background.
A woman wearing The Signature Undershirt from Numi, a gray fitted t-shirt featuring a hip length, sweat-proof material, reversible neckline, short seamless sleeves with a raw edge, and a slim fit ideal for layering.
Image split in half: the left side features a close-up of The Signature Undershirt's beige sweat-proof underarm shield by Numi in action, while the right side shows a model wearing a beige top. Text highlights product benefits like effective sweat protection, exceptional comfort, and versatile heat-friendly layering options.
Close-up of The Signature Undershirt by Numi in beige, with text detailing features: sweat-proof, all-day comfort, lightweight, 4-way stretch, thermo-regulating material to manage heat, and a durable design to prevent shrinking and fading.
Comparison chart showing Numi's The Signature Undershirt vs. Other T-Shirts. The Signature Undershirt by Numi features built-in underarm shields to stop sweat stains and odors, provides comfortable invisible shields, has seamless sleeves, and is made from breathable fabric.
A person with long dark hair poses with one arm raised, wearing The Signature Undershirt by Numi in light beige, and looking off to the side.
A woman with long dark hair stands facing forward, wearing a light beige short-sleeve top and light brown pants against a plain background. Her Signature Undershirt by Numi ensures she stays comfortable even in the heat, thanks to its sweat-proof design.
A person with long, dark hair is shown from the back wearing The Signature Undershirt in light pink and matching bottoms from Numi against a plain background.
A woman wearing The Signature Undershirt from Numi, a gray fitted t-shirt featuring a hip length, sweat-proof material, reversible neckline, short seamless sleeves with a raw edge, and a slim fit ideal for layering.
Image split in half: the left side features a close-up of The Signature Undershirt's beige sweat-proof underarm shield by Numi in action, while the right side shows a model wearing a beige top. Text highlights product benefits like effective sweat protection, exceptional comfort, and versatile heat-friendly layering options.
Close-up of The Signature Undershirt by Numi in beige, with text detailing features: sweat-proof, all-day comfort, lightweight, 4-way stretch, thermo-regulating material to manage heat, and a durable design to prevent shrinking and fading.
Comparison chart showing Numi's The Signature Undershirt vs. Other T-Shirts. The Signature Undershirt by Numi features built-in underarm shields to stop sweat stains and odors, provides comfortable invisible shields, has seamless sleeves, and is made from breathable fabric.

The Signature Undershirt

$70.00
A woman wearing Numi's sweat-proof light pink
Rear view of a person with long dark hair wearing The Crop Undershirt by Numi in light pink, paired with beige leggings, standing against a plain background.
Person with long dark hair wearing a white Numi Crop Undershirt and light brown pants, standing against a plain background.
A person with long dark hair is seen from behind wearing The Crop Undershirt by Numi, paired with beige pants against a plain background.
A woman wearing a black pair of pants and
A woman wearing the Numi Crop Undershirt in beige demonstrates its sweat-proof, odor-resistant underarm shields. Icons highlight the fabric's sweat and stain protection, comfort, cost-saving benefits, and suitability for layering.
The Crop Undershirt - Numi
The Crop Undershirt - Numi
A woman wearing Numi's sweat-proof light pink
Rear view of a person with long dark hair wearing The Crop Undershirt by Numi in light pink, paired with beige leggings, standing against a plain background.
Person with long dark hair wearing a white Numi Crop Undershirt and light brown pants, standing against a plain background.
A person with long dark hair is seen from behind wearing The Crop Undershirt by Numi, paired with beige pants against a plain background.
A woman wearing a black pair of pants and
A woman wearing the Numi Crop Undershirt in beige demonstrates its sweat-proof, odor-resistant underarm shields. Icons highlight the fabric's sweat and stain protection, comfort, cost-saving benefits, and suitability for layering.
The Crop Undershirt - Numi
The Crop Undershirt - Numi

The Crop Undershirt

$65.00
The Square Neck Cap Sleeve Undershirt - Numi
The Square Neck Cap Sleeve Undershirt - Numi
The Square Neck Cap Sleeve Undershirt - Numi
The Square Neck Cap Sleeve Undershirt - Numi
The Square Neck Cap Sleeve Undershirt - Numi
The Square Neck Cap Sleeve Undershirt - Numi
The Square Neck Cap Sleeve Undershirt - Numi
The Square Neck Cap Sleeve Undershirt - Numi

The Square Neck Cap Sleeve Undershirt

$70.00
A person with short dark hair and fair skin is wearing The Lace Undershirt by Numi, a white sweat-proof short-sleeve top, paired with beige pants, standing against a plain backdrop.
A woman with short dark hair is standing with her back turned, wearing a white, sweat-proof undershirt called The Lace Undershirt from Numi and light brown shorts against a plain background.
A woman in
A person with long dark hair is wearing The Lace Undershirt by Numi in beige, paired with matching sweat-proof pants, and standing against a plain light background.
A person with long dark hair, wearing a beige short-sleeve top over The Lace Undershirt by Numi and light brown pants, viewed from the back against a plain light background.
A woman wearing The Lace Undershirt by Numi, featuring short cap sleeves, a reversible neckline, a slim fit perfect for layering as an undershirt, and elegant lace trim detailing.
Image showing a woman wearing The Lace Undershirt by Numi in light beige. Features highlighted include sweat-proof and stain protection, all-day comfort, time and money savings, and easy layering. Text at bottom reads:
The Lace Undershirt - Numi
The Lace Undershirt - Numi
A person with short dark hair and fair skin is wearing The Lace Undershirt by Numi, a white sweat-proof short-sleeve top, paired with beige pants, standing against a plain backdrop.
A woman with short dark hair is standing with her back turned, wearing a white, sweat-proof undershirt called The Lace Undershirt from Numi and light brown shorts against a plain background.
A woman in
A person with long dark hair is wearing The Lace Undershirt by Numi in beige, paired with matching sweat-proof pants, and standing against a plain light background.
A person with long dark hair, wearing a beige short-sleeve top over The Lace Undershirt by Numi and light brown pants, viewed from the back against a plain light background.
A woman wearing The Lace Undershirt by Numi, featuring short cap sleeves, a reversible neckline, a slim fit perfect for layering as an undershirt, and elegant lace trim detailing.
Image showing a woman wearing The Lace Undershirt by Numi in light beige. Features highlighted include sweat-proof and stain protection, all-day comfort, time and money savings, and easy layering. Text at bottom reads:
The Lace Undershirt - Numi
The Lace Undershirt - Numi

The Lace Undershirt

$70.00

As Featured In

EMBARRASSING Sweat-Stains & Deo Disasters?

Wave them goodbye

The Signature Undershirt acts as a protective shield, preventing any unwanted stains from reaching your clothes. Our innovative fabric technology wicks away moisture, preserving your favorite outfits and extending their lifespan.

No Sweat Stains? How?

Secret Sweat Proof Shields

Our undershirts have a discreet and ultra-comfortable underarm sweat protection shield. Crafted from Contemporary Cotton™, a unique technical fabric that absorbs sweat and resists odors, our shields employ a one-way moisture transfer system, effectively redirecting moisture and sweat away from the body and keeping your clothing fresh for longer.

Thermo-Regulating.      4-Way Stretch.

Stay ahead of sweat with our advanced technology. Crafted from 90% Thermo-Regulating Tencel™, a supremely soft, breathable, and lightweight fabric that maintains your body temperature, ensuring you stay cool and dry throughout the day. The addition of 10% Lycra® offers optimal 4-way stretch and unmatched comfort for the ultimate layering essential.

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Feel your best in any situation

Say goodbye to embarrassing sweat stains and deodorant marks

As women, we understand the unspoken struggles of sweat-stains and deodorant marks, especially in social interactions. The signature undershirt, with its sweat-absorbing technology seamlessly integrated into the fabric, stands as your reliable ally against embarrassing stains and lasting comfort.

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A Resounding Hit

I Love the fit and materials of my Numi classic shirt. It really protects the outerwear sweaters and jackets and other long sleeves from my sweat.. That says a lot.!!

Brooke L.

✓ Verified Purchase

I had a blouse that showed perspiration stains - it was frustrating to use adhesive pads. I am beyond happy with my signature undershirt. It is lightweight, comfy and works to prevent perspiration stains, just as advertised. Best part? Canadian company and made in Canada!

Alison T.

✓ Verified Purchase

Bought this to wear under sweaters and it is perfect! Soft, stretchy and comfy. I’ll be buying more.

Leslie B.

✓ Verified Purchase

A person with long dark hair poses with one arm raised, wearing The Signature Undershirt by Numi in light beige, and looking off to the side.
A woman with long dark hair stands facing forward, wearing a light beige short-sleeve top and light brown pants against a plain background. Her Signature Undershirt by Numi ensures she stays comfortable even in the heat, thanks to its sweat-proof design.
A person with long, dark hair is shown from the back wearing The Signature Undershirt in light pink and matching bottoms from Numi against a plain background.
A woman wearing The Signature Undershirt from Numi, a gray fitted t-shirt featuring a hip length, sweat-proof material, reversible neckline, short seamless sleeves with a raw edge, and a slim fit ideal for layering.
Image split in half: the left side features a close-up of The Signature Undershirt's beige sweat-proof underarm shield by Numi in action, while the right side shows a model wearing a beige top. Text highlights product benefits like effective sweat protection, exceptional comfort, and versatile heat-friendly layering options.
Close-up of The Signature Undershirt by Numi in beige, with text detailing features: sweat-proof, all-day comfort, lightweight, 4-way stretch, thermo-regulating material to manage heat, and a durable design to prevent shrinking and fading.
Comparison chart showing Numi's The Signature Undershirt vs. Other T-Shirts. The Signature Undershirt by Numi features built-in underarm shields to stop sweat stains and odors, provides comfortable invisible shields, has seamless sleeves, and is made from breathable fabric.
A person with long dark hair poses with one arm raised, wearing The Signature Undershirt by Numi in light beige, and looking off to the side.
A woman with long dark hair stands facing forward, wearing a light beige short-sleeve top and light brown pants against a plain background. Her Signature Undershirt by Numi ensures she stays comfortable even in the heat, thanks to its sweat-proof design.
A person with long, dark hair is shown from the back wearing The Signature Undershirt in light pink and matching bottoms from Numi against a plain background.
A woman wearing The Signature Undershirt from Numi, a gray fitted t-shirt featuring a hip length, sweat-proof material, reversible neckline, short seamless sleeves with a raw edge, and a slim fit ideal for layering.
Image split in half: the left side features a close-up of The Signature Undershirt's beige sweat-proof underarm shield by Numi in action, while the right side shows a model wearing a beige top. Text highlights product benefits like effective sweat protection, exceptional comfort, and versatile heat-friendly layering options.
Close-up of The Signature Undershirt by Numi in beige, with text detailing features: sweat-proof, all-day comfort, lightweight, 4-way stretch, thermo-regulating material to manage heat, and a durable design to prevent shrinking and fading.
Comparison chart showing Numi's The Signature Undershirt vs. Other T-Shirts. The Signature Undershirt by Numi features built-in underarm shields to stop sweat stains and odors, provides comfortable invisible shields, has seamless sleeves, and is made from breathable fabric.

The Signature Undershirt

$70.00
A woman wearing Numi's sweat-proof light pink
Rear view of a person with long dark hair wearing The Crop Undershirt by Numi in light pink, paired with beige leggings, standing against a plain background.
Person with long dark hair wearing a white Numi Crop Undershirt and light brown pants, standing against a plain background.
A person with long dark hair is seen from behind wearing The Crop Undershirt by Numi, paired with beige pants against a plain background.
A woman wearing a black pair of pants and
A woman wearing the Numi Crop Undershirt in beige demonstrates its sweat-proof, odor-resistant underarm shields. Icons highlight the fabric's sweat and stain protection, comfort, cost-saving benefits, and suitability for layering.
The Crop Undershirt - Numi
The Crop Undershirt - Numi
A woman wearing Numi's sweat-proof light pink
Rear view of a person with long dark hair wearing The Crop Undershirt by Numi in light pink, paired with beige leggings, standing against a plain background.
Person with long dark hair wearing a white Numi Crop Undershirt and light brown pants, standing against a plain background.
A person with long dark hair is seen from behind wearing The Crop Undershirt by Numi, paired with beige pants against a plain background.
A woman wearing a black pair of pants and
A woman wearing the Numi Crop Undershirt in beige demonstrates its sweat-proof, odor-resistant underarm shields. Icons highlight the fabric's sweat and stain protection, comfort, cost-saving benefits, and suitability for layering.
The Crop Undershirt - Numi
The Crop Undershirt - Numi

The Crop Undershirt

$65.00
The Square Neck Cap Sleeve Undershirt - Numi
The Square Neck Cap Sleeve Undershirt - Numi
The Square Neck Cap Sleeve Undershirt - Numi
The Square Neck Cap Sleeve Undershirt - Numi
The Square Neck Cap Sleeve Undershirt - Numi
The Square Neck Cap Sleeve Undershirt - Numi
The Square Neck Cap Sleeve Undershirt - Numi
The Square Neck Cap Sleeve Undershirt - Numi

The Square Neck Cap Sleeve Undershirt

$70.00
A person with short dark hair and fair skin is wearing The Lace Undershirt by Numi, a white sweat-proof short-sleeve top, paired with beige pants, standing against a plain backdrop.
A woman with short dark hair is standing with her back turned, wearing a white, sweat-proof undershirt called The Lace Undershirt from Numi and light brown shorts against a plain background.
A woman in
A person with long dark hair is wearing The Lace Undershirt by Numi in beige, paired with matching sweat-proof pants, and standing against a plain light background.
A person with long dark hair, wearing a beige short-sleeve top over The Lace Undershirt by Numi and light brown pants, viewed from the back against a plain light background.
A woman wearing The Lace Undershirt by Numi, featuring short cap sleeves, a reversible neckline, a slim fit perfect for layering as an undershirt, and elegant lace trim detailing.
Image showing a woman wearing The Lace Undershirt by Numi in light beige. Features highlighted include sweat-proof and stain protection, all-day comfort, time and money savings, and easy layering. Text at bottom reads:
The Lace Undershirt - Numi
The Lace Undershirt - Numi
A person with short dark hair and fair skin is wearing The Lace Undershirt by Numi, a white sweat-proof short-sleeve top, paired with beige pants, standing against a plain backdrop.
A woman with short dark hair is standing with her back turned, wearing a white, sweat-proof undershirt called The Lace Undershirt from Numi and light brown shorts against a plain background.
A woman in
A person with long dark hair is wearing The Lace Undershirt by Numi in beige, paired with matching sweat-proof pants, and standing against a plain light background.
A person with long dark hair, wearing a beige short-sleeve top over The Lace Undershirt by Numi and light brown pants, viewed from the back against a plain light background.
A woman wearing The Lace Undershirt by Numi, featuring short cap sleeves, a reversible neckline, a slim fit perfect for layering as an undershirt, and elegant lace trim detailing.
Image showing a woman wearing The Lace Undershirt by Numi in light beige. Features highlighted include sweat-proof and stain protection, all-day comfort, time and money savings, and easy layering. Text at bottom reads:
The Lace Undershirt - Numi
The Lace Undershirt - Numi

The Lace Undershirt

$70.00

Looking your best has never been easier

Numi Undershirts are discreetly designed, ensuring no bulges or seams are visible under your clothing. You can confidently wear any outfit, knowing that your secret weapon is providing the perfect base-layer for a flawless appearance.

No Sweat Stains

Stay dry, confident, and stain-free with our unique cotton underarm shield. No more sweat stains, guaranteed.

Invisible Fit. 4-Way Stretch

Seamless sleeves and the ultra-soft four-way stretch fabric feels soft on the skin and works perfectly for layering

All Day Comfort

A long lasting & breathable fabric keeps you dry & cool all day long, no matter what life throws at you

The NUMI Undershirt

Changed the Lives of Thousands of Women

Join the community of women who have experienced the Numi difference, finding a dependable ally against embarrassing stains and lasting comfort.

BUY NOW

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FREE SHIPPING

On orders over $150

EASY RETURNS

Easy returns & exchanges on U.S. & Canada orders

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