Nordstrom’s loss will be Target’s gain at Stonestown Galleria.

Mall owner Brookfield Properties said the Seattle-based department store will close and that Target will expand into a big chunk of the space Nordstrom now occupies in the mall in southwestern San Francisco.

The Stonestown Target will triple from 30,000 square feet to 90,000 square feet. What will become of the rest of Nordstrom’s space — about 100,000 square feet — isn’t yet clear, although it could be filled with restaurants, entertainment and smaller stores, said Darren Iverson, a senior general manager with Brookfield. An existing below-ground-level Trader Joe’s is under the current Target space.

“Target has done very well at this property, so this presented a perfect opportunity for them to get more square footage,” said Iverson. “Everybody loves Target. It’s exciting times at Stonestown.”

Exciting, maybe, but also harrowing. Like malls across the country, Stonestown has tried to reinvent itself in the past few years. The mall’s other anchor, Macy’s, closed last year. Macy’s is being replaced by a Whole Foods, a Sports Basement, about 10 smaller retailers and an 11-screen Regal movie theater.

Target will keep its current space fronting 20th Avenue and expand into the ground level of Nordstrom, said Iverson.

Iverson said both Macy’s and Nordstrom were “great partners,” but at a time when shopping continues to migrate online, Stonestown is evolving to meet changing customer demand.

Macy’s and Nordstrom, along with JCPenney and Kohl’s, together have announced nearly 50 store closures this year.

Nordstrom said in a statement that the Stonestown store’s last day in business will be Sept. 13.

“Looking at our needs in the San Francisco market, we decided it made the most sense to close this store and focus on serving customers at our 20 other Nordstrom and Nordstrom Rack stores, as well as online,” the company said.

In San Francisco, Macy’s has sold off two of its Union Square properties and downsized both its men’s store and main store.

Most of the businesses replacing Macy’s at Stonestown will open in the second half of next year, and the larger Target will likely be up and running in early 2021.

As traditional retail wanes, Stonestown has become more of a foodie magnet, attracting more niche restaurants like the first U.S. outpost of Japanese chain Gram Cafe & Pancakes. Other recent openings include Yi Fang Taiwan Fruit Tea, Shihlin Taiwan Street Snacks, and Marugame Udon.

J.K. Dineen is a San Francisco Chronicle staff writer. Email: jdineen@sfchronicle.com Twitter: @sfjkdineen