Politicians are guilty of a "dereliction of duty" by failing to ensure the tech revolution has worked for everyone in society, London mayor Sadiq Khan will warn.
He will urge the likes of Facebook and Twitter to improve their response to criticism, or face the possibility of further regulation.
Khan will also warn Uber and other tech firms that all companies "must play by the rules" in the markets in which they operate.
The Labour mayor is the first British politician to give a keynote speech at the South by Southwest conference in Texas.
Khan is set to accuse politicians and governments of "sitting on their hands while the tech revolution has happened around them".
"It must ultimately fall to government - working with tech businesses and leaders - to ensure that this revolution is not detrimental to our long-term progress," he says in an early release of his speech.
"There's been a dereliction of duty on the part of politicians and policymakers to ensure that the rapid growth in technology is utilised and steered in a direction that benefits us all."
He will raise concerns over social media's role in influencing elections and referendums, spreading fake news and enabling extremists to radicalise and brainwash others.
"Facebook, Twitter and other platforms are finally starting to react to the criticisms and are developing technology to make sure the reporting process becomes quicker and more effective," he is expected to say.
"But with the skills and resources these companies have at their disposal, I believe it's possible to go further and faster."
Germany has recently introduced tough new laws so that social media companies face large fines if they fail to quickly remove things like hate speech.
