"I am aware that many perceive the power of Big Tech as overwhelming and impossible to roll back. I disagree," the EU executive said on Wednesday.
"We do not have to accept addictive features. We do not have to accept children being drawn into ever more extreme content. We do not have to accept that girls have their photos used for AI-generated sexualised images," she said.
Von der Leyen said that under her proposal "mini accounts" chaperoned by guardians would be granted to kids aged 13-15.
The EU's 27 member nations will now vote on the proposal, which could spark tensions with US President Donald Trump, who has long criticised Europe's tech regulations.
Von der Leyen used her speech to advance a plan that she foreshadowed earlier in 2026, when she said kids should be exposed to social media in a "phased and gradual" way.
The commission's proposal is part of a wider ongoing debate playing out worldwide on how to protect young people online.
In the United States, social media company Meta Platforms last month agreed to pay up to $US18 billion ($A25 billion) and add stronger child-safety measures to its Facebook and Instagram platforms to resolve a trial over teen social media addiction and settle claims filed by nearly every state.
Individual countries in Europe and in other places such as Australia and New Zealand have taken their own steps to ban teens from social media platforms.
But some of those efforts have run into roadblocks.
France's top court in August struck down a law banning children under 15 from social media, saying it infringed on fundamental freedoms.
French President Emmanuel Macron vowed to rework the proposal.
Manfred Weber, the head of the largest group in the European Parliament, spoke after von der Leyen to propose that the EU follow Australia's lead in allowing citizens to switch off social media algorithms.
"Elon Musk will not like it, but probably that is a reason for doing it," he said.
