On the bustling shopping strip of Fifth Avenue in New York City sits something you might not expect to find: an empty lot.

But it won’t stay empty for long. The development site at 570 Fifth Avenue, between 46th and 47th Streets, is slated to become a 33-story office tower, anchored by an 80,000-square-foot IKEA store at its base, according to the developer, Extell Development.

Ingka Investments, the real estate arm of Ingka Holding, the world’s largest IKEA franchisee, injected “approximately $400 million” into the overall project, said Extell’s founder and chairman, Gary Barnett. In exchange, Ingka scored a one-third stake in the building and ownership of its retail space.

“Having Ingka come in has been very helpful for us,” Mr. Barnett said. “They’ve injected a very substantial amount of equity. They’ve become our partner in the actual overall office deal, as well as purchasing their retail space.”

Ingka’s investment let Extell move forward with its office building, more than a decade after it first started buying up parcels for the development site, Mr. Barnett said. And it let Ingka secure a coveted slice of Fifth Avenue while keeping its popular furniture affordable.

“We can safeguard long-term stability for IKEA, keep overhead costs more predictable and maintain our commitment to providing accessible products,” said Jenna Grader, a portfolio manager at Ingka Investments.

Over the past year, competition for a handful of retail spaces on Fifth Avenue has heated up.

“They’re not making any more Fifth Avenues,” said Gary Phillips, said Gary Phillips, a managing director at Eastdil Secured who represented Extell in Ingka’s deal with his colleague Will Silverman. “It’s one of one.”

Luxury brands have been on a buying spree on the iconic stretch, as Curbed reported this year. Kering (the parent company of Gucci and Balenciaga) and Prada bought retail space from the real estate mogul Jeff Sutton, while LVMH (the parent company of Louis Vuitton) and Rolex intend to rebuild their Fifth Avenue flagships.

But it’s no longer just luxury fashion houses investing there, Mr. Silverman said. Geshary Coffee spent $38 million to buy 560 Fifth Avenue at the end of last year. Uniqlo entered into a contract in August to buy its 90,732-square-foot retail space at 666 Fifth Avenue for $350 million. And more deals may be in the works, with Brookfield Asset Management considering a sale of its building at 685 Fifth Avenue, Bloomberg reported.

“Fifth Avenue is effectively eternal,” said Mr. Silverman, who also brokered the Prada, Kering and Uniqlo deals with Mr. Phillips at Eastdil. “When the opportunity arises to secure a location that you’re sure you’ll want forever, why would you not think about securing it?”

Chasing those opportunities is clearly a part of Uniqlo’s strategy, said Zach Redding, a managing director at Colliers who represented the seller in Geshary’s 560 Fifth Avenue deal. (Uniqlo bought its flagship at 546 Broadway in 2021.)

“They clearly said to themselves, ‘We’re going to buy the stores that we want to be in — in irreplaceable locations,’” Mr. Redding said.