Facing an existential crisis over empty space, owners are trying to fill malls with residences, building on the live-work-play model sought by young adults.

The Westlake Shopping Center, which opened in the 1950s in Daly City, Calif., is one of the first modern malls in the country. Over the past seven decades, it has survived the rise of online retailers, the shuttering of anchor stores and operating restrictions related to the pandemic. Now comes its latest test: the addition of nearly 400 apartments.

The strategy, which is being closely watched by retail experts, is expected to increase foot traffic and generate more revenue from the new residents who may be more inclined to shop in their own neighborhood.

“They’re able to feed off each other,” said Conor C. Flynn, chief executive of Kimco Realty, the real estate investment trust that owns the mall. “It’s almost like an ecosystem where the customer shops your retail, the retailers will support the apartments and drive a premium for the apartments.”

At the Westlake Shopping Center, Kimco plans to turn the space that was once the Burlington Coat Factory into a 214-apartment complex. Kimco had already received approval from Daly City to build its first set of apartments, and the trust worked with Burlington to relocate the off-price retailer to the front of the mall, giving it space to build even more apartments and still have room for nearly 11,000 square feet of retail and restaurant space, Mr. Flynn said. In total, Westlake will have about 400 apartments.

Mr. Flynn has made it a priority for Kimco to find ways to add residences to its 550 properties. Now, the mall owner is building about 1,000 apartments a year and taking a ground-lease approach, meaning that it works with a third-party developer to construct the apartments. Its goal is to have 15,000 apartments that are approved or built by 2025.

Kimco’s redevelopment strategy is reaping benefits: Last year, foot traffic across its portfolio was up just 0.6 percent from the year before, but it rose 5.3 percent at properties that have a mixed-use element, the company said.