(WSJ) Billionaire George Soros’s investment firm has agreed to spend up to $300 million on an Argentine hotel company’s Latin America expansion, a vote of confidence in a region that has been suffering slow economic growth and waning investor interest.

The investment by Mr. Soros will help finance as many as 5,000 new hotel rooms in Peru, Chile, Ecuador, Argentina and other South American countries within the next three years, according to Fen Hotels Chief Executive Patricio Fuks. His Buenos Aires-based hospitality company will manage the properties.

By focusing on Latin America, Mr. Fuks thinks he can get a lot more for his partner’s money than in other parts of the world. New hotel acquisition or construction in major U.S. cities is increasingly competitive and expensive, he said, “but you can still build for a reasonable price in Latin America’s capital cities.”

Property costs are cheaper there for a reason. The region’s economies have slumped as the global commodity boom has wound down amid slowing demand from China and much foreign investor money has rushed for the exits. Brazil, the continent’s biggest economy, has been particularly hard hit.

Economists have been cutting near-term growth forecasts for most countries in the region, a bearish sign for regional travel. But Mr. Soros’s commitment to develop thousands of hotel rooms over the next three years in South America suggests some seasoned investors are already banking on these countries’ eventual rebound.

“They were looking to get into the region,” said Mr. Fuks.

A spokesman for Soros Fund Management LLC declined to comment.

Mr. Soros, a Hungarian-born investor, is famous for his 1992 bet against the British pound that made him about $1 billion after the U.K. government withdrew the currency from the European monetary system. A few years ago he converted his hedge-fund company to a family office.

Other Latin American lodging brands are also starting to expand beyond their borders. Grupo Posadas S.A.B. de C.V., Mexico’s largest hotel company, in June said it was teaming with private-equity firm Bighorn Capital Inc. to open up to 10 luxury hotels in the U.S. over the next five years.

Brazil’s luxury hotelier Fasano, meanwhile, is preparing to take over as operator of the famed Shore Club in Miami Beach, its first project outside South America.

Fen Hotels is also looking to establish a presence in the U.S., with its Dazzler brand property in Brooklyn and other hotels in Miami and Los Angeles.

But Mr. Fuks sees more opportunity closer to home. Fen Hotels already has 35 hotels across Latin America, making it a big player in countries where family-owned and operated properties are still the norm and many of the big global chains have only a few toes in the water.

Mr. Fuks, however, said he is steering clear of Brazil. Not because he is bearish on the market but because he sees it as the most crowded playing field in the region.

“Brazil is too expensive to develop there,” he said. “But if it turns around, the other countries will follow.”

Mr. Fuks grew up in Argentina. His father was in the construction business and also owned a hotel in Buenos Aires, where the son worked the front desk and acquired a taste for the hospitality business.

In 2003, he launched Fen Hotels in the capital city and expanded with lifestyle properties that focused on design and a lively bar and restaurant scene but priced at the same level as big box properties like Sheraton and Hilton.

The region’s poor economic times carry another silver lining for Fen Hotels. The properties are hiring top chefs from Argentine and sending them to its hotels in the U.S. They are happy to go, Mr. Fuks said, “to get good work during a recession.”