SYDNEY, AUSTRALIA—Visitors to Uluru, a giant sandstone slab jutting from the central Australian desert, have for decades ignored a sign at the rock’s base that politely reads: “Please don’t climb.”

On Wednesday, the board members of Uluru-Kata Tjuta National Park, which manages the popular site also known as Ayers Rock, said they would soon stop requesting that hikers respect the landmark. Instead, they will demand it.

Beginning in 2019, climbing Uluru, which is considered sacred to the region’s Indigenous Anangu people, will be banned, the board said.

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“It is an extremely important place,” said Sammy Wilson, an Indigenous community representative who sits on the park’s board and is what is known as a traditional owner. Uluru, he said, is “not a theme park like Disneyland.”

Climbing the 347-metre-tall rock in Australia’s Northern Territory will be banned as of Oct. 26, 2019, a historically significant date for the site. On that day in 1985, the government returned ownership of Uluru to the Anangu people. As part of that agreement, the Anangu lease the site back to the government, and the two parties jointly manage it.

Uluru has, for many in Australia, come to symbolize the struggle for Indigenous rights. Mr. Wilson said some people in the government wanted to keep the rock open to hikers, but “it’s not their law that lies in this land.”

Traditional owners do not climb Uluru out of respect, and they worry that hiking will damage the stone. Uluru-Kata Tjuta National Park is a UNESCO World Heritage Site.

There has been opposition to the climbing ban. Last year, Adam Giles, a politician with an Indigenous heritage who was then the Northern Territory chief minister, called the idea “ludicrous.”

But Sally Barnes, Australia’s director of national parks, said it was a “significant moment for all Australians” that “marks a new chapter in our history.”

“It clearly says we put country and culture first when managing this place for all Australians and our visitors from around the world,” she said on Wednesday.

About 250,000 people visit Uluru every year, according to the park’s website. In recent years, the number of visitors wishing to climb the rock has dropped significantly, to less than 20 per cent, according to Ms. Barnes. Tour operators now offer alternatives to climbing Uluru, including camel tours around its base.

“The best view of Uluru is from the bottom,” one social media user said on Wednesday.