UK Prime Minister Keir Starmer said that children under-16s will be banned from social media.
"A full ban is the right choice," the prime minister said, adding "this is not something I do lightly", he said, reports the BBC.
TikTok, Snapchat and Instagram are among the apps that could be included.
The measures are part of the government's plans to protect young people from harm online and address unhealthy late-night scrolling on phones
A consultation, which concluded earlier this year and had more than 116,000 responses, found that 85% of parents believe the risk of social media outweigh the benefits
Australia became the first country in the world to introduce a similar ban in December last year.
The BBC's Zoe Kleinman asks when the ban will start, how it will work and what he'll do if one of the bigger platforms decides to leave the UK.
Starmer says powers have been taken to ensure the government "can move at speed".
"We hope to pass regulation before Christmas," he says, adding the ban will therefore come into place early next year.
Before moving on to questions Keir Starmer said:
"I want this message to be heard loud and clear. I am not prepared to compromise on the safety and happiness of our children, and that is why this ban must happen, and why this ban will happen."
Starmer added "it won't be easy" and that some tech companies want people to think things are "unchangeable".
"We have to resist that kind of learned helplessness," he said.
"We have agency", Starmer said, adding that the government "can" and "will" change things.
"Yes it's hard" to legislate for, regulate and enforce but that's why the government "listened to people" and learned from countries like Australia, he says, where a similar ban has already been introduced.
"We're not just bringing forward a ban" but "going further" with "world-leading action" on gaming services and live streaming platforms, Starmer said.
Changes will also tackle platforms which allow strangers to contact any child "unchecked", he added.
Ban will be 'welcomed by parents'
"In this world, with this technology, it is hard as a parent to know what to do", Starmer says.
"I think most parents will welcome this", he adds.
But he adds the government still believes it must "harness the power of technology to build a stronger, fairer Britain".
The prime minister is now taking questions from journalists in Downing Street, and we'll bring you a few more lines from his speech in a moment.
'I feel for this generation', Starmer says
Starmer says social media stops children from doing their homework, reading, playing with their friends, and going to bed at a decent hour.
"That may not sound like much, but these are activities that help a child develop into an adult," he says.
"To be honest, I feel for this generation," he adds. Thinking back to his own childhood, Starmer says children didn't have to deal with this type of technology that feeds into daily life.
Starmer says a full ban is the right choice and came to the decision as a parent himself.
"All I've ever wanted for my own children, hand on heart, is for them to be happy and for them to be safe, I think that's what any parent wants."
He asks if it can be believed that social media creates a safe environment for children, "I don't think I even need to answer those questions do I?"