Facebook Inc., which owns Instagram, two years ago began experimenting with hiding likes in the hope that it might be good for users’ mental health and reduce anxiety about the popularity of their posts, Instagram head

Adam Mosseri

said.

He said the company was willing to make the change even if it proved detrimental to its business interests.

“The hope here was to try and depressurize the experience a little bit,” Mr. Mosseri said on a call with reporters ahead of the feature’s formal rollout. “It turned out that it didn’t actually change nearly as much about the experience in terms of how people felt or how much they use the experience as we thought it would.”

Hiding likes proved controversial among Instagram users during the feature’s testing, he said, with some account holders embracing the disappearance of a key popularity metric and others complaining that it robbed them of information about posts’ relevance. On Instagram, users click on a heart symbol to convey that they like a post.

Despite concerns that public like counts might be harmful, surveys of user well-being didn’t budge, Mr. Mosseri said, nor did Instagram usage meaningfully change.

“I think we had a sense that we were going to lose users,” Mr. Mosseri said. “It doesn’t look like we are going to.”

Mr. Mosseri said that Instagram chose to go forward with giving users the ability to hide likes as a matter of personal choice.

“It’s important to us that people feel good about the time that they spend on Instagram or on Facebook,” Mr. Mosseri said.

With almost three billion monthly users, Facebook is the world’s largest social-media company.

The company’s formal introduction of the option to hide likes comes as it and rival social-media platforms face scrutiny over their products’ effects on mental health and in particular their impact on children. Some researchers have argued that social-media usage can trigger depression or other harms, and both lawyers and members of Congress have raised objections to Instagram’s plan to build a version of its product for children below the age of 13.

Mr. Mosseri has said that a responsibly designed platform for tweens would help keep them off Instagram’s main platform. He said concerns about Facebook’s overall impact on its users’ well-being are likely overblown, but said that Instagram was committed to studying it.

“We’re going to continue to try and work with external academics and researchers,” he said.

Users will be able to hide both likes on their own posts and on those of the people they follow, he said. Mr. Mosseri said Instagram expects a double-digit percentage of users to end up hiding likes.

Instagram users in some countries will start being shown the option to hide likes starting on Wednesday, Mr. Mosseri said, with the feature being rolled out across the world within a few days. In countries where Instagram has already hidden likes, including Brazil, Canada and Japan, users will instead be asked if they’d like to opt back into them.

Write to Jeff Horwitz at Jeff.Horwitz@wsj.com