Police will now be able to read encrypted messages from suspected terrorists, paedophiles and other serious criminals on WhatsApp, Facebook and other social media.
Home Secretary Priti Patel will sign an agreement between the UK and the US next month which which will force the tech giants to hand over information to the police.
Downing Street views the data access agreement as an invaluable tool in the fight against terrorism and sexual abuse.
Ms Patel and former head of counterterrorism at the Metropolitan Police, Richard Walton, say that the social media companies were previously empowering terrorism.
Currently police are only able to access social media messages if there is an immediate threat to life in an 'emergency disclosure'.
Police and prosecutors can also ask to see social media data under the 'mutual legal assistance' treaty but that can take up to two years.
The new treaty will see police and prosecutors submit requests for information to a judge while being overseen by the investigatory powers commissioner.
Both the US and the UK have agreed not to target people from each other's countries.
The UK has also assured that any information the US gets about British companies cannot be used in cases that may end in a death penalty sentence.
The signing of the new treaty comes just two months after the sentencing of Stephen Nicholson - who was jailed for life for killing 13-year-old Lucy McHugh.
Police criticised Facebook throughout their investigation for refusing to release messages sent to Lucy by main suspect Nicholson.
After applying to US courts for access to his account, his messages weren't revealed until the day his trial began but it is believed that he was able to delete a lot of them.
He was then swiftly convicted.
Mr Walton told the : 'US tech giants have been inadvertantly putting a veil over serious criminality and terrorism.
'It has tilted the balance in favour of criminals and terrorists. This is welcome, it will make a big difference.'
And last month a just in a child sex abuse trial said that social media firms were guilty of showing 'misplaced loyalty to customers', according to the Times.
Compiled by Olalekan Adeleye