Jens and Emma Grede sweep into a side room at the upmarket Claridge’s hotel in London with a phalanx of personal assistants, makeup artists and friends in tow.

Their names may not be familiar, but the couple are the multimillionaire co-founders and co-owners of Kim Kardashian’s lingerie and loungewear brand Skims, which is already worth £3bn – more than designer label Tom Ford or outdoorwear brand Patagonia – even though it is just four years old. Skims was named one of Time magazine’s most influential companies last year.

Kardashian, the US socialite and businesswoman, is the co-owner, fitting model and creative adviser to the brand, known for its figure-moulding shapewear. She also promotes it through her considerable social media reach (she has 364 million Instagram followers).

Jens Grede, who is Skims’s chief executive, and Kardashian together control a majority stake in the business, and Emma’s personal fortune is more than $350m (£275m), although their exact holdings are undisclosed. The Gredes’s marketing abilities have taken them from both dropping out of college to buying Brad Pitt’s former Malibu holiday home for $45m last year, adding to their $24m Bel Air mansion.

There has been talk that Skims – which is on track to bank sales of $750m in 2023, in another dramatic step up from the near-$500m taken last year – will seek a stock market listing before long, which is likely to make their names much more prominent.

Jens says he believes Skims, which now employs 200 people, “deserves” to be publicly listed but that there is no rush to float.

The Los-Angeles headquartered business has tapped into the trend for celebrity-fronted brands, which has created juggernauts including Rihanna’s Fenty Beauty, Kylie Jenner’s cosmetics line and Pharrell Williams’s position at Louis Vuitton.

Having appeared more than once on Shark Tank in the US and its BBC equivalent, Dragons’ Den, London-born Emma is becoming a business influencer in her own right. She has also used her role as Shark Tank’s first Black female presenter to highlight her work with the 15 Percent Pledge, her initiative to persuade US retailers to reserve 15% of their shelf space for Black-owned businesses.

Casually but expensively dressed and immaculately groomed, the Gredes pose for the Observer’s photographer with the expertise and focus of the influencers they spend time with. They ask for a glimpse at the images, and a makeup artist steps in to tweak an out-of-place hair.

Together for 16 years, the Gredes have built an empire on linking famous names with products to supercharge sales, and they clearly buy into a lifestyle where image is everything.

Skims aims to combine body-sculpting technology with comfort and the kind of style that makes consumers unafraid to put their underwear on show.

The Gredes decry the idea that its success is simply due to celebrity pulling power, however.

“Talent can bring you to a product once, but you don’t come back time and time again,” says Emma.

“You have got to be offering superior product at a price and value people really understand.”

“If it were easy, every celebrity would have a billion-dollar brand,” adds Jens.

The pair are well entrenched in the Kardashian clan, who became one of the world’s most famous families through their long-running reality TV show.

Having met Kim’s mother, Kris Jenner, through her marketing agency work, Emma had launched denim brand Good American with another of Jenner’s daughters, Khloé Kardashian, in 2016.

The couple moved to Los Angeles, where they live with their four children, the following year, and Emma and Kim soon struck up a friendship which would lead to the birth of Skims.

Emma remains a co-owner, as well as the company’s chief product officer.

The pair moved to the US to build their business – but also partly in reaction to Brexit, which Jens, who is Swedish, says made him feel differently about living in his adopted homeland of the UK. “I had built a big company and was a good taxpayer and citizen. The fact that it was felt that wasn’t worth anything – I took that personally,” he says.

The couple still make plenty of trips across the Atlantic as they build the Skims brand, which is now set to move well beyond its heartland on social media into the high street, with its first permanent physical store, set to open next year on Sunset Boulevard in LA. Another three could follow in 2024 after experiments with pop-ups this year, including one in Selfridges in London.

Also on the cards is the launch of Skims menswear in October, after the couple realised that 12% of sales already went to men, who buy items such as socks and pyjamas or the more gender-fluid “boyfriend” styles already available.

The Gredes joined forces from different worlds. Jens, the son of a film director and an artist, grew up in Sweden, while Emma – whose dad was a BT engineer while her mum worked on the Swiss trading desk at Morgan Stanley – grew up in Plaistow, east London. She attended the local comprehensive school and dreamed of becoming a fashion designer, but dropped out of the London College of Fashion in order to work, initially in PR.

“I was hustling seven days a week from 15 to 18. Before I got a job at a fashion show production company, I did the rounds,” she says. “I went around crossing off the jobs I didn’t want to do.”

She helped put together London fashion week shows, and later linked designers and other well known names with high street brands and events.

Meanwhile, Jens had started out working at men’s magazines in Sweden before coming to London for the launch of Tyler Brûlé’s Wallpaper* magazine in 1996.

He moved into consulting with GQ Style and Vogue and worked on campaigns for Calvin Klein and Louis Vuitton, co-founding the marketing agency Saturday Group (now Wednesday Agency) in 2003.

Emma joined the agency in the mid-00s, and the pair worked together for about a year before becoming a couple. Her talent partnership deals included linking actor Natalie Portman with Dior.

After seeing friends set up their own fashion brands, Jens decided to have a go himself with the launch of luxury denim brand Frame in 2012, taking advantage of the growth of Instagram to promote the business.

Emma saw that success and was inspired to have a go herself, taking a chance to promote more diverse talent and products that could fit a broader range of people by founding the Good American label as a reaction against fashion campaigns which were “rooted in inclusivity and diversity, using plus-size models, but didn’t make clothes to fit those people”.

The brand was also a first step towards acquiring the kind of fortune and power she was used to sitting alongside.

“In my career I was fortunate to have a front-row seat with an address book of celebrity brands and talents,” she says.

“We were building ideas and creating value for other companies all the time, and I thought, ‘Let’s take what I know and go and create value for myself.’”

CV

Age Emma: 40. Jens: 45.
Family Four children.
Education Both dropped out of college – Emma at 17, Jens at 20.
Pay Not disclosed.
Last holiday European summer travels that took them to London, Ibiza and Paris.
Best advice they have been given “Always reinvent yourself on the way up.”
Phrases they overuse Emma: “FFS!” Jens: “I don’t know much, but …”
How they relax Emma: reading (currently The Covenant of Water). Jens: going to the gym.