Buy 3+ Undershirts and get 30% off your order.
Use code BUNDLE30

Buy 3: Save $58

Buy 4: Save $78

Buy 5: Save $97

Buy 6: Save $117

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

$70.00
$70.00

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.

Color

stops 100% of sweat stains*

Absorbs moisture & odor

Lightweight& breathable

4-waystretch

*Based on moderate to heavy sweaters

Free Shipping

On orders over $150

Easy Returns

On U.S. & Canada orders

Risk-Free

100% Money Back Guarantee

As Featured In

A Resounding Hit

"This was my first Numi purchase and I couldn't be happier! These undershirts are comfortable and really help extend the life of my clothes by reducing washing."

Lauren A.

✓ Verified Purchase

“Underarm shields are well-made and beautifully constructed. Unlike other products on the market, they are cut low in back and front and along the side of the collar so they don't peak through the overgarment.”

Tanyss L.

✓ Verified Purchase

“I got this shirt because I use natural deodorants and they don't work as well as antiperspirants. This shirt protects my blouse and keeps me odor free.”

Jaclyn G.

✓ Verified Purchase

FEEL YOUR BEST

Why wear a Numi undershirt?

With each undershirt boasting innovative stain prevention and freshness technology, having a variety equips you for any situation. From workdays to workouts, having extras ensures you're constantly armed with confidence and ready to take on the day, no matter what it brings

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Secret Sweat 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

TENCEL™

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.

4-Way Stretch

Invisible Fit

Our undershirts are designed to fit snug to the body and be invisible under your clothes. Seamless Sleeves And The Ultra-Soft Four-Way Stretch to provide greater freedom of movement. Fabric Feels Soft On The Skin And Works Perfectly For Layering. 

Feel Your Best

Bid farewell to the constant annoyance of sweat stains and deodorant marks and forget about the anxiety of unexpected blemishes that erode your confidence. Embrace a realm of limitless comfort through our innovative design, ensuring you remain fresh and stain-free all day long.

Don’t miss out! Take advantage of our offer before it expires

Buy 3+ Undershirts and get 30% off your order

FAQs

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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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