The environmental campaign group has called for drivers to either not use the major road from 7am on Wednesday or to reduce their speed to 20mph “to minimise the risk of accidents”.
In a statement, the group said: “In light of a national injunction covering England’s highways, Insulate Britain has declared the M25 a site of nonviolent civil resistance and called for motorway traffic to be slowed.
“Starting from 7.00 on the morning of Wednesday 27 October the M25 will become a place of nonviolent civil resistance to stop our government committing crimes against humanity.
“We ask that: People do not use the M25, or if they do, speeds are reduced to 20mph to minimise the risk of accidents.”
Insulate Britain called on Highways England to enforce the proposed 20mph speed limit and asked the police to “refuse to arrest us”.
In return, the environmental activists vowed emergency blue light access would be maintained throughout the demonstration.
Transport secretary Grant Shapps on Monday announced another injunction had been granted against Insulate Britain protesters, covering the “entire strategic road network”.
It came after the group renewed its roadblock campaign the same day, bringing traffic on the streets of the City of London and Canary Wharf to a standstill.
The Met said 53 people were arrested at protest sites in Bishopsgate, Upper Thames Street, Limehouse Street and Southwark Bridge.
The campaign group, an offshoot of Extinction Rebellion, wants the government to insulate all UK homes by 2030 to cut carbon emissions and has been staging protests for several weeks including on motorways and at the Port of Dover.
But the demonstrations have led to clashes with the public, including drivers who have dragged protesters out of the road.
The protests on Monday were the organisation’s first since temporarily halting activities for 10 days from 14 October.
The group had blocked roads on 14 days over the five weeks to 14 October, with activists often gluing their hands to the carriageway to increase the length of time it took for police to remove them.
Hundreds of arrests were made, with some people detained several times.
The campaign continues despite injunctions leaving protesters facing court summons and possible imprisonment or an unlimited fine.
Additional reporting by Press Association
Register for free to continue reading
Registration is a free and easy way to support our truly independent journalism
By registering, you will also enjoy limited access to Premium articles, exclusive newsletters, commenting, and virtual events with our leading journalists
Already have an account? sign in
Join our new commenting forum
Join thought-provoking conversations, follow other Independent readers and see their replies