Insulate Britain blocked the anti-clockwise exit slip road at junction 18, Chorleywood, Hertfordshire.
A separate protest took place near junction four (Stanborough Interchange) of the A1(M), near Hatfield.
The protest is the fourth time the climate activists have blocked various parts of the motorway.
Insulate Britain wrote to the Highways Agency and the relevant Police forces on Sunday, informing them that the campaign would continue, and specified that supporters would be on the M25 network on Monday from 7am.
Insulate Britain are asking the Highways Agency to review their previous decision not to reduce speed limits, even though they had been made aware that major disruption will be taking place.
Given that this is a standard safety procedure when hazards occur on the motorway, Insulate Britain is surprised it has not formed part of the response to the campaign.
The letter read: “We are writing from the campaign group Insulate Britain. People’s safety during this campaign has always been our primary objective.
"Therefore, on the 16th September we passed a request to the police to slow down the traffic on the south west parts of the M25 network, as we were aware that supporters of the Insulate Britain campaign would be participating in acts of civil disobedience in that area.
"In the context of the horror of the climate crisis we believe that it is entirely proportionate to create disruption on the motorway network if it means the UK Government fulfils its legal obligation of staying below 2°C which will stop the unimaginable suffering for future generations.
"Our request was refused.
"We write now to request that you review this decision, as campaign supporters will be on the M25 network on Monday 20th September from 7am.
"Thank you for your time on this matter.
"The Insulate Britain campaign.”
Twenty-four people were arrested on Friday morning following incidents on two of the county’s motorways.
Surrey Police said: "We were called at 8.37am by a member of the public reporting people in the carriageway at junction 9 of the M25.
"Within 15 minutes, Surrey Police officers had arrested 14 people on suspicion on a variety of offences including criminal damage, causing danger to road users, wilful obstruction of the highway and causing a public nuisance, and the motorway was running freely shortly afterwards.
We then received a further call shortly after 9am reporting protesters at junction 1 of the M3. Officers were on the scene by 9.10am to swiftly and safely resolve the situation.
"Ten people were arrested on suspicion of a number of offences including criminal damage, causing danger to road users, wilful obstruction of highway and causing a public nuisance. Traffic was flowing freely again by 9.24am."
Chief Superintendent Jerry Westerman added: “This week has seen significant levels of protest activity on critical roads in the region. Protesters arrived in Surrey from all over the country including as far away as Cornwall and Yorkshire, and we took swift and robust action to ensure protesters were removed from two major roads in the county after they ignored our requests to move on peacefully.
"In both cases this morning, we re-opened the roads as quickly as it was safe to – with traffic flowing freely within twenty five minutes of our receiving a call about the protesters on the M3.
“I would like to reassure the public that our priority is a quick and effective response, with disruption kept to a minimum. Officers responded quickly this morning to make arrests in these two situations, as well as monitoring the wider motorway network.
“We continue to collect evidence to ensure anyone breaking the law is brought to justice and I’d like to appeal to anyone who may have captured dashcam footage of either of today’s protests before police arrived at the scenes. Please contact us on 101, through a private message on our social media channels or the live chat on our website if you can help.
“I would like to thank road users for their patience and understanding this week; I appreciate the frustration you feel being caught up in delays, and I want to reassure you we’re doing all we can.
“Thank you also to colleagues in other forces and our other partner agencies like Highways England."