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Men's Base Layer Bottoms

(34 products)
Products (34)
Sort: Best Match
  • Sale Ends May 25
    Top Rated
    REI Co-opLightweight Base Layer Bottoms - Men's
    $33.69
    Save 25%
    compared to  $44.95
    28 reviews with an average rating of 4.6 out of 5 stars
    Underwear Weight:
    Lightweight
    Size Type:
    Regular, Big, Tall
  • Sale Ends May 25
    Top Rated
    SmartwoolClassic Thermal Merino Base Layer Bottoms - Men's
    $93.69
    Save 25%
    compared to  $125.00
    647 reviews with an average rating of 4.7 out of 5 stars
    Underwear Weight:
    Midweight
    Size Type:
    Regular, Big
  • Sale Ends May 25
    REI Co-opMerino 185 Base Layer Bottoms - Men's
    $59.89
    Save 25%
    compared to  $79.95
    169 reviews with an average rating of 4.2 out of 5 stars
    Underwear Weight:
    Lightweight
    Size Type:
    Regular, Big
  • Sale Ends May 25
    Top Rated
    REI Co-opMidweight Base Layer Bottoms - Men's
    $41.19
    Save 25%
    compared to  $54.95
    105 reviews with an average rating of 4.5 out of 5 stars
    Underwear Weight:
    Midweight
    Size Type:
    Regular, Big, Tall
  • Sale Ends May 25
    SmartwoolClassic All-Season Merino Base Layer Bottoms - Men's
    $74.99
    Save 25%
    compared to  $100.00
    30 reviews with an average rating of 4.3 out of 5 stars
    Underwear Weight:
    Lightweight
    Size Type:
    Regular, Big
  • Text reads: ‘Anniversary Sale 2026. 25% off’ over a collage of Smartwool long-sleeve shirts and colorful socks.

    Save 25% on all Smartwool clothing

    Arc'teryxRho LT Base Layer Bottoms - Men's
    $59.83 - $100.00
    61 reviews with an average rating of 4.4 out of 5 stars
    Underwear Weight:
    Lightweight
    Size Type:
    Regular, Big
    Top Rated
    PatagoniaCapilene Midweight Base Layer Bottoms - Men's
    $89.00
    Add to cart to see price
    60 reviews with an average rating of 4.6 out of 5 stars
    Underwear Weight:
    Midweight
    Size Type:
    Regular
    tasc PerformanceElevation Merino Base Layer Bottoms - Men's
    $46.73 - $54.73
    Save 30% - 40%
    compared to  $79.00
    44 reviews with an average rating of 3.9 out of 5 stars
    Underwear Weight:
    Lightweight
    Size Type:
    Big, Regular
    REI OUTLET
  • Sale Ends May 25
    Top Rated
    IcebreakerMerino 200 Oasis Base Layer Leggings with Fly - Men's
    $89.99
    Save 25%
    compared to  $120.00
    87 reviews with an average rating of 4.7 out of 5 stars
    Underwear Weight:
    Midweight
    Size Type:
    Regular, Big
  • Sale Ends May 25
    SmartwoolClassic All-Season Merino 3/4 Base Layer Bottoms - Men's
    $63.69
    Save 25%
    compared to  $85.00
    5 reviews with an average rating of 4.2 out of 5 stars
    Underwear Weight:
    Lightweight
    Size Type:
    Regular, Big
  • Sale Ends May 25
    SmartwoolIntraknit Thermal Merino Base Layer Bottoms - Men's
    $97.49 - $112.49
    Save 25% - 35%
    compared to  $150.00
    33 reviews with an average rating of 4.4 out of 5 stars
    Underwear Weight:
    Lightweight
    Size Type:
    Regular, Big
  • Sale Ends May 25
    Top Rated
    Icebreaker260 Merino Tech Thermal Leggings with Fly - Men's
    $104.99
    Save 25%
    compared to  $140.00
    73 reviews with an average rating of 4.7 out of 5 stars
    Underwear Weight:
    Heavyweight
    Size Type:
    Regular, Big
  • Sale Ends May 25
    REI Co-opMerino 185 Base Layer Bottoms - Men's Tall Sizes
    $59.89
    Save 25%
    compared to  $79.95
    17 reviews with an average rating of 3.9 out of 5 stars
    Underwear Weight:
    Lightweight
    Size Type:
    Tall, Big
    Top Rated
    REI Co-opHeavyweight Merino Base Layer Bottoms - Men's
    $99.95
    21 reviews with an average rating of 4.7 out of 5 stars
    Underwear Weight:
    Heavyweight
    Size Type:
    Regular, Big, Tall
    PatagoniaCapilene Thermal Weight Long-Underwear Bottoms - Men's
    $99.00
    Add to cart to see price
    16 reviews with an average rating of 4.1 out of 5 stars
    Underwear Weight:
    Heavyweight
    Size Type:
    Regular, Big
  • Sale Ends May 25
    Top Rated
    SmartwoolClassic Thermal Merino 3/4 Base Layer Bottoms - Men's
    $86.19
    Save 25%
    compared to  $115.00
    87 reviews with an average rating of 4.7 out of 5 stars
    Underwear Weight:
    Midweight
    Size Type:
    Regular, Big
  • Sale Ends May 25
    SmartwoolIntraknit AS Merino Base Layer Bottoms - Men's
    $93.69
    Save 25%
    compared to  $125.00
    2 reviews with an average rating of 5.0 out of 5 stars
    Underwear Weight:
    Midweight
    Size Type:
    Regular, Big
    SmartwoolClassic Thermal Merino 3/4 Base Layer Bottoms - Men's
    $78.73
    Save 25%
    compared to  $105.00
    0 reviews
    Underwear Weight:
    Midweight
    Size Type:
    Regular, Big
    REI OUTLET
    Mountain HardwearUp First Tech Fleece Base Layer Bottoms - Men's
    $74.73
    Save 25%
    compared to  $100.00
    4 reviews with an average rating of 4.5 out of 5 stars
    Underwear Weight:
    Midweight
    Size Type:
    Regular, Big
    REI OUTLET
    Top Rated
    Arc'teryxRho Insulated 3/4 Base Layer Bottoms - Men's
    $159.73
    Save 20%
    compared to  $200.00
    13 reviews with an average rating of 4.6 out of 5 stars
    Underwear Weight:
    Heavyweight
    Size Type:
    Big, Regular
    REI OUTLET
    Black DiamondCoefficient LT One Piece Base Layer - Men's
    $149.73
    Save 31%
    compared to  $219.00
    10 reviews with an average rating of 3.3 out of 5 stars
    Underwear Weight:
    Lightweight
    Size Type:
    Regular
    REI OUTLET
    Free CountryCloud Knit Base Layer Bottoms - Men's
    $20.73
    Save 48%
    compared to  $40.00
    3 reviews with an average rating of 5.0 out of 5 stars
    Underwear Weight:
    Lightweight
    Size Type:
    Big
    REI OUTLET
    SmartwoolIntraknit Active Base Layer Bottoms - Men's
    $81.73
    Save 25%
    compared to  $110.00
    4 reviews with an average rating of 4.5 out of 5 stars
    Underwear Weight:
    Midweight
    Size Type:
    Big
    REI OUTLET
    Arc'teryxRho SV Base Layer Bottoms - Men's
    $69.83
    Save 41%
    compared to  $120.00
    1 reviews with an average rating of 2.0 out of 5 stars
    Underwear Weight:
    Heavyweight
    Size Type:
    Big
    Helly HansenLIFA Base Layer Pants - Men's
    $45.00
    0 reviews
    Underwear Weight:
    Lightweight
    Size Type:
    Regular, Big
    Arc'teryxRho LT Base Layer Bottoms - Men's
    $79.73
    Save 20%
    compared to  $100.00
    11 reviews with an average rating of 3.9 out of 5 stars
    Underwear Weight:
    Midweight
    Size Type:
    Big
    REI OUTLET
  • Limited time only! The R E I Co-op Mastercard.

    Get $130 in value

    When approved for the REI Co-op Mastercard by May 25, you’ll get $30 in card rewards. Plus, you can earn a $100 REI gift card after your first non-REI purchase within 60 days from account opening. Terms apply.

    Ortovox185 Rock'N'Wool Short Base Layer Pants - Men's
    $100.00 - $110.00
    0 reviews
    Underwear Weight:
    Lightweight
    Size Type:
    Regular, Big
    Top Rated
    KUHLReactiv Lite Grid Base Layer Bottoms - Men's
    $99.00
    5 reviews with an average rating of 4.6 out of 5 stars
    Underwear Weight:
    Lightweight
    Size Type:
    Regular, Big
    TerramarC-Suite Mammoth Sherpa Fleece Mid-Layer Pants - Men's
    $56.73
    Save 29%
    compared to  $80.00
    2 reviews with an average rating of 3.0 out of 5 stars
    Underwear Weight:
    Midweight
    Size Type:
    Regular, Big
    REI OUTLET
    Ortovox120 Comp Light Short Base Layer Pants - Men's
    $70.00
    3 reviews with an average rating of 5.0 out of 5 stars
    Underwear Weight:
    Lightweight
    Size Type:
    Regular, Big
1–30 of 34 products
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