10 Best Silk Thermal Underwear 2026 in the United States

The Icebreaker Women’s 175 Everyday Leggings are crafted from 100% Merino wool, known for being soft, lightweight, and excellent at regulating body temperature. This makes them a strong choice for year-round wear, especially in activities like running, skiing, yoga, or hiking where managing moisture and staying comfortable is key. The 175 weight indicates a balance between warmth and lightness, suitable for moderately cool conditions without overheating.

The leggings have a slim, snug fit with rib fabric that stretches comfortably, making them good for layering under other clothing without bulk. Moisture-wicking is a standout feature here—Merino wool naturally pulls sweat away from the skin, helping you stay dry in various weather. The leggings are machine washable but need gentle care such as cold wash and flat drying to maintain their quality.

These leggings are an excellent choice for women seeking a natural, comfortable base layer with effective temperature control and moisture management. They are especially suitable if you prefer lightweight thermal wear for everyday outdoor or active use.

The METWAY Women's Silk Long Johns set is made from 100% natural mulberry silk, known for being soft, lightweight, and breathable. This material quality makes it comfortable to wear for long periods, especially for those with sensitive or allergy-prone skin, since mulberry silk is hypoallergenic and gentle. The fit is close to the body, designed to feel like a second skin, which helps trap warmth without bulk—great as a base layer in cold weather or for sleeping. The set includes a V-neck top and long bottoms, both stretchy enough to move with you.

Moisture-wicking is naturally strong thanks to silk’s absorbent nature, helping keep you dry and comfortable. Seam construction isn’t specifically detailed but the knitted fabric’s elasticity should reduce irritation from seams. For care, it’s best to wash gently by hand or on a machine’s delicate cycle and air dry, avoiding bleach to maintain the fabric’s quality.

Sizing is important to check before buying to ensure the right snug fit. Though priced a bit higher than synthetic thermal underwear, this set provides excellent comfort and natural warmth, making it ideal for those looking for a soft, breathable layer during winter without irritation.

This Women’s Pure Mulberry Silk Knitted Thermal Underwear Set is made from 100% high-quality silk, which feels very smooth and soft against the skin. Silk is naturally gentle and doesn’t cause irritation, making it a great choice if you have sensitive skin. The fabric is lightweight and stretchable, thanks to a 4-way stretch design, so it moves well with your body and fits comfortably as a base layer. It’s designed to keep you warm by regulating your natural body temperature while also wicking away moisture effectively, which helps to keep your skin dry during chilly nights or outdoor activities.

The fabric’s special knit also adds breathability and maintains the silk’s natural shine and elasticity. On the downside, the underwear requires careful washing—hand washing is recommended and hang drying is a must to avoid damage since the fabric is thin and delicate. The pull-on design is simple but it may not suit everyone’s fit preferences without trying it on first.

This set is ideal for anyone looking for a lightweight, comfortable thermal layer that feels luxurious and works well to keep warm and dry, especially if you don’t want bulkier synthetic materials. Just be prepared to handle it gently when washing to preserve its quality.