As the apparel company prepares to expand into physical stores and men’s clothing, its latest funding round may spur questions about when it intends to go public.

Four years into its existence, Skims, the apparel company co-founded by Kim Kardashian, has become a unicorn four times over.

Skims has raised $270 million in a new funding round that values it at $4 billion, the company plans to announce on Wednesday. That’s up from the $3.2 billion valuation investors gave the company last year.

Ms. Kardashian and her business partner, Jens Grede, have sought to turn Skims into the next big apparel brand.

“It has grown quickly, and we’re so proud of that,” Ms. Kardashian said in an interview. “We’ve had a really good flow of product launches.”

The company started as a seller of shapewear to help customers fit into body-hugging clothing. But shapewear no longer represents a majority of its sales: Skims has expanded into an array of clothing categories, including loungewear and swimwear, with plans to branch out into men’s clothing this fall.

And once known for selling directly to consumers, Skims is making a bet on physical retail, with plans to open its first flagship stores next year in Los Angeles and New York City.

Mr. Grede, who is Skims’s chief executive, said in an interview that the company was now profitable and on track for $750 million in sales this year, up from $500 million in 2022. About 15 percent of its online customers come from outside the United States, and nearly 70 percent of its overall customers are millennials or Gen Z-ers.

Over the last year, he said, 11 million people have joined wait-lists to buy the brand’s most popular items, which often sell out.

It is that growth trajectory and popularity that drew investors to the company when executives began raising money in recent months, Mr. Grede said. The asset manager Wellington Management led the latest round. Other participating firms include Greenoaks Capital Partners and the existing backers D1 Capital Partners and Imaginary Ventures.

“Skims has maintained unprecedented momentum since the brand’s inception,” Michael Carmen, a co-head of private investments at Wellington, said in a statement. “We’re thrilled to partner with the brand to support it through this pivotal growth stage.”

Skims’s success has been among the biggest standouts in Ms. Kardashian’s business empire, which now includes skin care, fragrances and even a private equity firm. Already minted as a billionaire after Skims’s 2021 fund-raising round, Ms. Kardashian remains the company’s single biggest shareholder, and together she and Mr. Grede still own a majority stake.

Early on, Skims had to contend with pandemic-driven supply-chain disruptions that made it hard to source fabrics for its clothing.

Significant challenges now, according to Ms. Kardashian and Mr. Grede, include managing inventory as the company expands its offerings and opens physical stores, as well as competing against companies offering steep discounts as consumers cut back on discretionary spending in the face of high inflation. It is a problem that has bedeviled many retail companies, and will become more pressing as Skims opens its own stores, Ms. Kardashian said.

Skims’s latest investment is likely to spur questions about when it intends to go public, given both the company’s swelling valuation and the involvement of Wellington, which is known for investing in companies before they go public. The apparel maker has taken other steps typical of businesses setting themselves up for initial offerings, including hiring a chief financial officer last year.

Mr. Grede demurred on the topic of timing, saying he and Ms. Kardashian were in no rush. But he noted that investors had shown interest in recent months in consumer-facing businesses.

And going public remains one of the company’s goals. “At some point in the future, Skims deserves to be a public company,” he said.