The Tinkers' Heart, overlooking Loch Fyne, is a pattern of quartz stones that has lain since the 1700s.
Travellers have used the site as a wedding place, or a spot to bless children or remember the dead.
Historic Scotland initially rejected monument status but reconsidered after campaigners were backed by MSPs on Holyrood's Public Petitions Committee.
Author Jess Smith was one of the leading figures in the campaign to have the site protected.
Petitions committee convener John Pentland said: "This is an outstanding result for Jess Smith and the committee greatly welcomes the new status of the Tinkers' Heart as a monument of national importance.
"Following pressure from Jess Smith, and the committee, Historic Scotland made a fresh appraisal of the Tinkers' Heart.
"The committee particularly welcomes the increased co-operation between Jess Smith, Historic Scotland and the landowner of the Tinkers' Heart site, which has led to such a positive solution."
Mr Pentland said members of the committee looked forward to "visiting the Tinkers' Heart and celebrating its new status" later in the year.
A travellers site in Argyll has been awarded national monument status after campaigners lobbied MSPs.