Exclusive: 5 reasons why this startup became one of the fastest selling underwear brands in the UK.

A woman buys a pair of Underdays underwear every minute in the UK, here's why women are choosing to ditch their M&S underwear and switch to the social media-disrupter brand Underdays.


Jump to section quickly:

Today, we're diving into the success of underwear-disrupter Underdays. If you haven't already seen them all over your social-media feed, they are the new challenger brand in the UK taking on Marks & Spencer and Victoria's Secret. Underdays isn't just another fast fashion underwear brand – it's a revolution that's redefining comfort, style, and body positivity.

Whether you’re already a die-hard fan or never head of them before, these 5 surprising facts will give you a whole new perspective on why everyone your social media feed is wearing this underwear. Let’s unravel the secrets behind this success story!

Fact #1: The Origin of Innovation – Solving a Personal Dilemma

"Underdays began not in a high-end designer studio, but from a real-life challenges faced by founders Amelie Salas and Oria Mackenzie who quit their jobs in luxury fashion to start the brand. Frustrated by the lack of comfortable and stylish options on the market. They were tired of choosing between beige high street basics or uncomfortable sexy lingerie. Why can't women have it all? They were fustrated that women had all these other incredible products in their lives, but the ones that touched the most intimate areas were often of the poorest quality.

This personal struggle sparked the idea for Underdays – a brand that would offer, comfortable, breathable and ultra-flattering underwear solutions for women of all shapes and sizes. This journey from a simple fix to a fashion revelation laid the foundation for what Underdays is today – a brand built on the ethos of innovation, inclusivity, and personal experience."

Embracing Every Body

Underdays commitment to inclusivity is not just a trend, it's a mission. The brand's size range goes from XS - XXL and more sizes are on the way.

Revolutionizing Comfort

At the heart of Underdays lies innovation. Every product released is there to solve a problem and fits within their mission to bring you unparalleled comfort and style with no more compromises.

Eco-Friendly Fashion

Underdays isn't just about looking good, it's about doing good too. Their underwear is made from a natural fabric, which uses 20x less water than cotton. It's also designed for durability and to last many years, which means less consumption and less replacements.

Unmatched Quality

Every Underdays piece is made out of a luxurious micro-modal, a natural fabric designed to be twice as soft cotton. The fabric is designed for enhanced breathability, wicking away moisture and keeping you fresher for longer.

Everyday Confidence

Underdays is more than just underwear – the unmatched breathability and flattering fits are designed to make you feel confident and empowered in your everyday life.

Fact #2: Setting the Bar High – Surpassing Competitors with Unmatched Innovation

Underdays didn't just enter the underwear market; it redefined it. While the market was saturated with traditional underwear and lingerie brands, Underdays brought a fresh perspective that set it apart from competitors. Instead of following the 'one-size-fits-all' approach, Underdays sought to encourage women to ditch their cheap high street underwear and invest in their most intimate parts for the first time, working closely with a gynaecologist to design their underwear and create pairs that guarantee all-day freshness.


  • Unrivalled breathability & freshness
  • Soft leg elastics
  • Durability
  • Flattering shapes for every body

Other Brands

  • Fabrics that trap moisture & breed infections
  • Side seams that dig in
  • Only lasts a few washes
  • Conventional Cuts

Fact #3: Leveraging Social Media Influence

"Underdays' marketing strategy is a textbook example of modern branding success. Unlike traditional advertising methods often used by its competitors, Underdays capitalizes on the power of social media and influencer marketing. Leveraging a community of women and having many "it-girls" and micro influencers wear their underwear. The brand creates buzz and visibility in ways that many competitors can't match.

Underdays has effectively turned every product launch into a viral event, creating a level of hype and anticipation that traditional marketing seldom achieves."

Fact #4: Commitment to Body Positivity

The brand's commitment to body positivity is a game-changer. Underdays celebrates and embraces diverse body types, challenging the industry's longstanding beauty standards.

Unlike some competitors that perpetuate unrealistic ideals, Underdays champions authenticity and inclusivity. It actively showcases real people of all sizes and backgrounds wearing its products, inspiring confidence and self-expression.

Fact #5: Sustainability as a Priority

As the fashion industry faces increasing scrutiny for its environmental impact, Underdays is taking a stand by prioritizing natural fabrics that use no harmful chemicals and less water than traditional fabrics like cotton. Additionally, Underdays focuses on creating durable, long-lasting products that stand the test of time, discouraging fast fashion trends that contribute to excessive waste.