If implemented, the measures would place the United Kingdom at the forefront of global efforts to regulate young people's online activity, going beyond similar policies adopted in countries such as Australia.
Speaking to reporters on Monday, Starmer argued that the changes are necessary to protect children from online harms and reduce the influence of technology on their daily lives.
"It is clear to me a full ban is the right choice," he said.
"It will make a huge difference, it will make our children safer, it will make our children happier, it will give them more time, more security, more freedom to grow up, more opportunity."
A Wider Ban Than Australia's
The proposed legislation would prohibit children under 16 from accessing major social media platforms, including YouTube, Facebook, X, Instagram, Snapchat and TikTok.
Unlike Australia's landmark social media ban, Britain's proposal would also target gaming platforms and livestreaming services where children can interact with strangers online.
Officials said the government is considering additional safeguards for users under 18, including overnight restrictions and limits on addictive features such as infinite scrolling.
Starmer said the goal is to address risks that many parents would never tolerate in the physical world.
"Is there a situation in the offline world where you would just let your child pair up with a stranger, an adult that you don't know anything about?" he asked.
The government also announced what it described as "world-leading blocks" on livestreaming and unsolicited contact between adults and children online.
However, messaging platforms such as WhatsApp and Signal are expected to remain exempt from the proposed ban.
Enforcement Challenges Remain
Despite the government's confidence in the plan, questions remain over how effectively the restrictions can be enforced.
Starmer acknowledged that some children would inevitably find ways around the rules but argued that legislation could still create a long-term cultural shift in attitudes toward social media use.
"Laws are rules, but they're also an expression of our values," he said.
Officials indicated that the ban could take effect as early as next spring, supported by existing legal powers and additional regulations expected before the end of the year.
The proposals would likely require broader age-verification systems across online platforms, similar to measures already introduced by communications regulator Ofcom for adult websites.
Ofcom said it stands ready to support implementation if the government proceeds.
Tech Companies Push Back
The announcement was met with resistance from some of the world's largest technology companies, which argue that an outright ban could have unintended consequences.
Several firms warned that preventing teenagers from using mainstream platforms could drive them toward less regulated services with weaker safety protections.
A spokesperson for YouTube highlighted the platform's existing safety measures.
"YouTube has invested in expert-led, age-appropriate experiences and default protections for teens for over a decade," the company said.
"YouTube is a vital resource for young people, educators and parents."
Snapchat also questioned whether a blanket ban was the best solution.
The company argued that much of the time teenagers spend on Snapchat involves private communication with friends and family, adding that policymakers should carefully examine the scope of the restrictions.
Meta, the parent company of Facebook and Instagram, pointed to lessons from Australia's experience, warning that bans could isolate teenagers from online communities while pushing them toward unregulated alternatives lacking parental controls and safety features.
Experts Divided on Effectiveness
While public concern over children's online safety has grown significantly in recent years, researchers remain divided over whether a complete ban would achieve the desired outcomes.
Some psychologists and digital researchers argue that evidence linking social media restrictions to improved wellbeing remains inconclusive.
Amy Orben, a Research Professor at the University of Cambridge, noted that enforcement efforts in Australia are still evolving and that many young people continue to access online platforms at similar rates despite restrictions.
"However, a ban is likely to change public perceptions, and make social media use less acceptable in younger age groups," she said.
The debate reflects a broader global discussion about balancing child protection, freedom of access, education and digital participation.
Part of a Growing Global Trend
Britain has steadily tightened regulations on technology companies in recent years, pressuring platforms to modify algorithms, strengthen child safety measures and prevent the sharing of harmful content among minors.
The proposed social media ban marks the latest step in that broader regulatory push.
A growing number of governments around the world are exploring similar measures amid mounting concerns about the impact of social media on children's mental health, safety, sleep patterns and overall development.
For Starmer, the policy could become one of the defining initiatives of his premiership. As political pressure mounts at home, the prime minister is framing the crackdown as a long-term effort to reshape the relationship between young people and technology.
Whether the ban ultimately succeeds may depend not only on enforcement, but also on whether it changes social norms around children's online behaviour in the years ahead.