The lone demonstrator unfurled a banner reading “Climate Assembly, be bold” on Thursday morning.
The group are calling for a more radical approach from Scotland’s Climate Assembly, a body created as part of the 2019 Climate Change Act.
The protester is understood to have climbed down from the roof before being arrested by police officers waiting at the parliament’s entrance.
A Police Scotland spokesperson said: “Officers were called to the Scottish Parliament building Edinburgh, around 7.35am on Thursday March 4 2021, following reports a person was on the roof.
“A 61-year-old man has been arrested and inquiries continue.”
A photo from the scene earlier this morning showed a group of police officers at the scene in Edinburgh.
XR said they planned to remain on the roof of Holyrood until 11am.
Kate Dyer, a member of the group, said: “This is the moment where we actually have a real chance of circumventing the status quo of traditional politics which is only committed to not rocking the boat.
“The citizens sitting in this assembly have a chance to respond to the root causes of this emergency and turn the ship around.”
She added: “We are asking assembly members to be bold.”
A spokesperson for Scotland’s Climate Assembly said: “Scotland’s Climate Assembly has deliberated on a broad range of robust and complex evidence over the past several months.
“Our members - more than 100 people from all walks of life across Scotland - are now working hard to agree their recommendations for how the country should tackle the climate emergency in an effective and fair way.
“Of course we welcome a lively public debate on these vital issues.”
They added: “The Assembly operates independently, following a rigorous process based on international best practices for participatory democracy, and it is for members alone to decide their recommendations.”
Activists from XR previously climbed onto the roof of the Scottish Parliament in October 2020, unveiling a Trainspotting-style banner that read “Choose Oil or Choose Life”.