Long underwear for women has become an essential part of winter wardrobes, providing warmth and comfort during chilly months. In 2025, the best options combine advanced materials with stylish designs, ensuring that women stay cozy without sacrificing fashion. From moisture-wicking fabrics to thermal insulation, these top picks cater to various activities, whether you're hitting the slopes or enjoying a casual day outdoors. Brands like Smartwool, Patagonia, and Under Armour lead the way with their innovative designs and sustainable practices, making them favorites among outdoor enthusiasts and everyday wearers alike.
Smartwool Men's Classic Thermal Merino Base Layer Crew, Charcoal Heather, Small
- COLD WEATHER BASE LAYER. We've updated this fan-favorite with new colors and a new fit to improve functionality while enhancing aesthetics. Add this cold weather base layer to your winter wardrobe and experience the difference on your next adventure.
- SLIM FIT. Designed to meet the demands of outdoor adventuring, this slim fit crewneck shows off a slimming silhouette while offering unrestricted movement through the arms and chest.
- CLASSIC THERMAL MERINO. Ideal for cold-weather activities where warmth and breathability are crucial, this midweight fabric used a 100% Merino wool construction that helps move moisture away from skin to keep you warm and dry.
- FUNCTIONAL FEATURES. Go far, feel good with thoughtful tech to keep you trekking comfortably — interlock knitting enhances breathability, thermoregulation and moisture-wicking while flatlock seams minimize chafing for greater comfort.
- GO FAR. FEEL GOOD. From wool socks to base layers for men, women and kids, we aim to provide the highest quality apparel for your outdoor adventures with a commitment to environmental sustainability, racial equity and inclusivity.
$109.99
SALE
−$11.02
Smartwool SW016361001M Men's Merino 250 Baselayer Bottom Black M
- COLD WEATHER BASE LAYER. Keep your ski or hiking boots free of bulk and friction with our 3/4 Bottom. Merino wool provides ultimate comfort, while a newly redesigned base layer pants fit helps reduce sag and excess fabric—perfect for layering.
- SLIM FIT. Designed to meet the demands of outdoor adventuring, these slim fit bottoms show off a slimming silhouette while offering unrestricted movement through the legs. Inseam: 21.5"
- CLASSIC THERMAL MERINO. Ideal for cold-weather activities where warmth and breathability are crucial, this midweight fabric used a Merino wool construction that helps move moisture away from skin to keep you warm and dry.
- FUNCTIONAL FEATURES. Go far, feel good with thoughtful tech to keep you trekking comfortably — interlock knitting enhances breathability, thermoregulation and moisture-wicking while flatlock seams minimize chafing for greater comfort.
- GO FAR. FEEL GOOD. From wool socks to base layers for men, women and kids, we aim to provide the highest quality apparel for your outdoor adventures with a commitment to environmental sustainability, racial equity and inclusivity.
$103.98
Smartwool Merino 250 Base Layer Crew Twilight Blue Heather S
- COLD WEATHER BASE LAYER. Increase your comfort level with this 100% Merino wool crew. Add one of our best base layers for cold weather to your winter wardrobe and experience the difference the next time you go skiing, hiking, climbing, or biking.
- SLIM FIT. Designed to meet the demands of outdoor adventuring, this slim fit crewneck shows off a slimming silhouette while offering unrestricted movement through the arms and chest.
- MERINO WOOL. Soft and eco-conscious, wool is a sustainable wonder fiber that wicks moisture away and helps regulate body temperature from cold-weather camping to summer hiking.
- FUNCTIONAL FEATURES. Go far, feel good with thoughtful tech to keep you trekking comfortably — a back body seam wraps to the front for a body-enhancing fit while a flatlock seam construction minimizes chafing.
- GO FAR. FEEL GOOD. From wool socks to base layers for men, women and kids, we aim to provide the highest quality apparel for your outdoor adventures with a commitment to environmental sustainability, racial equity and inclusivity.
$109.99
Smartwool Merino 250 Base Layer Bottoms Twilight Blue Heather M
- COLD WEATHER BASE LAYER. With a fit that improves functionality while enhancing aesthetics for a range of body shapes, comfort is never in question. Get yourself a pair or two of our best base layer pants and conquer the cold with more confidence.
- MID RISE. Crafted with comfort in mind, this mid rise pant sits high on the hips just slightly below the belly button.
- SLIM FIT. Designed to meet the demands of outdoor adventuring, these slim fit bottoms show off a slimming silhouette while offering unrestricted movement through the legs. Inseam: 30.5"
- MERINO WOOL. Soft and eco-conscious, wool is a sustainable wonder fiber that wicks moisture away and helps regulate body temperature from cold-weather camping to summer hiking.
- FUNCTIONAL FEATURES. Go far, feel good with thoughtful tech to keep you trekking comfortably — a merino-covered elastic waistband offers maximum comfort while a flatlock seam construction minimizes chafing.
$115.00
SALE
−$30.00
Merino.tech Merino Wool Base Layer Mens Set - Heavyweight, Midweight, Lite Merino Wool Thermal Underwear For Men Top, Bottom (Large, 250 Black)
- Midweight: Mens Merino Base Layer Available in: Lightweight = 165 g/m², Midweight = 250 g/m², Heavyweight = 320 g/m². Free Merino Wool Hiking Socks ($21 Value) – Package includes Midweight Merino wool base layer mens top and wool men long johns 250 g/m² + Merino Wool Hiking Socks. Cool Packaging. Makes A Great Gift.
- Super Soft & Comfortable: 100% Superfine 17.5 Micron merino wool base layer set mens provides all day comfort and no itch! Merino wool long underwear men set was designed for daily wear without rubbing, overheating, or bunching of regular cotton.
- Moisture Wicking & Odor Resistant: Natural wicking and odor-resistant properties of merino wool thermal underwear allow it to absorb moisture better than any other fabric, keeping you dry and fresh.
- Breathable – For longer lasting wear, hand wash and lay flat to air dry. Mens wool long johns sets naturally regulate body temperature to keep you comfortable all year round.
- Zero Worries: Every we make merino wool base layer top mens and long johns are backed by our Merino.tech Promise - ensuring you're 100% happy with every Merino.tech purchase. For best results hand wash and lay flat to dry
$99.99
Smartwool SW016355001XL Men's Merino 250 Baselayer 1/4 Zip Black XL
- Odor-resistant
- Temperature regulating
- Will help keep you cool when your intensity amps up, and its design helps minimize chafing
$196.46
SALE
−$15.01
Smartwool Women's Merino 250 Baselayer 1/4 Zip Twilight Blue Heather Xl
- Women's Merino 250 Base Layer 1/4 Zip to improve functionality while also enhancing aesthetics. As one of our heaviest base layer tops and one of our best base layers for cold weather
- SW016373
- Flatlock seam construction designed to minimize chafing
- Slim Fit
- 100% Merino Wool
$99.99
Smartwool SW016365001S Men's Merino 250 Baselayer 3/4 Bottom Black S
- COLD WEATHER BASE LAYER. Keep your ski or hiking boots free of bulk and friction with our 3/4 Bottom. Merino wool provides ultimate comfort, while a newly redesigned base layer pants fit helps reduce sag and excess fabric—perfect for layering.
- SLIM FIT. Designed to meet the demands of outdoor adventuring, these slim fit bottoms show off a slimming silhouette while offering unrestricted movement through the legs. Inseam: 21.5"
- CLASSIC THERMAL MERINO. Ideal for cold-weather activities where warmth and breathability are crucial, this midweight fabric used a Merino wool construction that helps move moisture away from skin to keep you warm and dry.
- FUNCTIONAL FEATURES. Go far, feel good with thoughtful tech to keep you trekking comfortably — interlock knitting enhances breathability, thermoregulation and moisture-wicking while flatlock seams minimize chafing for greater comfort.
- GO FAR. FEEL GOOD. From wool socks to base layers for men, women and kids, we aim to provide the highest quality apparel for your outdoor adventures with a commitment to environmental sustainability, racial equity and inclusivity.
$105.00
Merino.tech Merino Wool Base Layer - Mens 100% Merino Wool Long Sleeve Thermal Shirts Heavyweight, Midweight, Lite with Socks (Medium, Black 250)
- Midweight: Mens Merino Base Layer Available in: Lightweight 165 g/m², Midweight 230-250 g/m², Heavyweight 320 g/m² Merino Wool Premium Hiking Socks ($21 Value) – Package includes Men's 250g/m² Merino Wool Base Layer Top Wool Socks. Cool Packaging! Makes A Great Gift!
- Super Soft & Comfortable: 100% Superfine 17.5 Merino Wool Mens Base Layer provides all day comfort and no itch! Designed for daily wear without rubbing, overheating, or bunching of regular cotton.
- Moisture Wicking & Odor Resistant: Merino base layer mens natural wicking properties allow it to absorb moisture better than any other fabric, keeping you dry and fresh.
- Easy Care: Washer safe. For longer lasting wear, hand wash and lay flat to air dry. Mens Wool Baselayer naturally regulates body temperature to keep you comfortable all year round.
- Zero Worries: Every Mens Merino Wool Base Layer we make is backed by our Merino.tech Promise - ensuring you're 100% happy with every Merino.tech purchase. For best results hand wash and lay flat to dry.
$58.99
SALE
−$23.01
Smartwool Women's Classic Thermal Merino Base Layer Pattern Crew Light Gray Mountain Scape L
- Fit updated to improve functionality while enhancing aesthetics for a range of body shapes. Crew neck with raglan sleeves
- SW016371
- Flatlock seam construction designed to minimize chafing. Back body seam wraps to front for body-enhancing fit
- Slim Fit
- 100% Merino Wool
$86.99
Last update on 2025-05-03 / Affiliate links / Images from Amazon Product Advertising API