European retailers are testing the waters of second-hand fashion in a bid to capitalize on more sustainability-minded consumers, but analysts see limited financial benefits in the short term.

Inditex’s brand Zara on Tuesday expanded its second-hand platform, Pre-Owned, in 14 countries including its home market, Spain. The business, which allows consumers to sell and repair their Zara garments as well as to donate clothes, was already implemented in the U.K. and France and has now been extended to other European markets.

Other companies that are betting on this trend are Sweden’s H&M Hennes & Mauritz with its platform Rewear, which aims to sell and buy pre-owned clothes from any brand, and German online fashion retailer Zalando.

Clothing retailers have been attracted into the second-hand market by a combination of consumer demand and sustainability concerns but, while the market is expected to grow at a fast clip in the coming years, analysts caution that profitability looks set to be challenging for now.

The global market of second-hand and resale apparel is expected to reach a value of $351 billion in 2027, almost doubling compared with the $177 billion it was estimated to be worth last year, according to data from Statista. This compares with estimated revenue in the apparel market worldwide of $1.74 trillion this year, according to Statista data.

“The market has quadrupled since 2017 and is expected to continue to grow massively in particular in Germany, U.K., Italy and France, mainly driven by young cohorts,” Achim Berg, advisor on global apparel, fashion and luxury at consultancy McKinsey, said in an interview.

Retailers want to be involved in the second-hand market so they can keep an eye on such trends, Societe Generale analyst Anne Critchlow told The Wall Street Journal.

“It allows them to understand what consumers want from this business, how popular it is and whether they should be offering it,” Critchlow said.

Zalando has seen growing demand since it added a second-hand section to its platform last year, especially with customers aged 18-29, it said.

“We are giving customers the opportunity to shop both pre-owned and new on the same platform,” the company said.

Although the launch of retailers’ own second-hand divisions seeks to satisfy customer demand, there are other factors involved such as meeting sustainability goals, Berg said.

The business model of the fashion industry consists in pushing volumes of new products to the market, although 20% of what is bought is never worn, Berg said. “This isn’t only about sustainability, but it is also about sustainability.”

In fact, 25% of the fabrics that enter in the supply chain end up as waste, according to a report by the United Nations.

Having products that are longer in the market through second-hand opportunities is definitely helpful and will be helpful for the companies’ sustainability goals, but it doesn’t solve the issue, the McKinsey advisor said.

The arrival of big companies brings more competition to the second-hand market, which isn’t a bad thing, especially for consumers and sustainability, Critchlow said. Retailers that specialize in second-hand clothes could end up benefiting given that the entrance of big names could make the category more popular, Berg said.

However, big retailers are still in a trial-and-error phase and profitability remains a challenge.

“Revenue for second hand is by definition limited, because essentially companies earn a commission on lower-value products, rather than selling the full-ticket price,” SocGen’s Critchlow said.

These companies seem to be able to make second-hand operations either break even or marginally profitable at this stage because they can use their logistics networks, like warehouses and delivery services, she added.

“Second-hand divisions can be marginally helpful for retailers, but I don’t think they are going to become a substantial part of their business over the next few years,” Critchlow said.

Write to Andrea Figueras at andrea.figueras@wsj.com