New powers will be given to the watchdog Ofcom to force social media firms to act over harmful content.
Until now, firms like Facebook, Tiktok, YouTube, Snapchat and Twitter have largely been self-regulating.
The companies have defended their own rules about taking down unacceptable content, but critics say independent rules are needed to keep people safe.
It is unclear what penalties Ofcom will be able to enforce to target violence, cyber-bullying and child abuse.
There have been widespread calls for social media firms to take more responsibility for their content, especially after the death of Molly Russell who took her own life after viewing graphic content on Instagram.
The government has now announced it is “minded” to grant new powers to Ofcom – which currently only regulates the media and the telecoms industry, not internet safety.