THE SIGNATURE UNDERSHIRT

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

Stay cool, dry, and fresh all day with our innovative sweat-proof undershirts. 

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

$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 $150+
(After discounts, before shipping & taxes)

As Featured In

No Sweat Stains? How?

Secret Sweat Shields

Our undershirts have a discreet sweat shield in the underarm made from special sweat absorbing technical fabric. This innovative feature offers added sweat protection and keeps your clothes clean longer.

TENCEL™

Remove sweat before it happens! TENCEL™ is a sumptuously soft, breathable fabric that regulates your body temperature, making it the perfect layering piece.

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

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.

Looking your best has never been easier

The Signature Undershirt is 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

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 Signature Undershirt

Changed the Lives of Thousands of Women

Join the women who have already experienced the Numi difference. Embrace confidence, stay dry, and make a positive impact on the planet.

BUY NOW

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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.
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