Dressed in civilian clothes and unarmed, the group of mainly young men arrived in the provincial centre of Bunia in several vehicles and signed the deal as stunned locals looked on.
As the convoy entered the city, shops and businesses promptly closed, the reporter said.
The group said they belonged to a defence organisation set up in 2019 to defend the interests of five communities which had been "victims of atrocities in Ituri" province near the border with Uganda.
The group, known as "Zaire," says it represents the Hema, Mambisa, Alur, Akongo-Nyali and Ndo-Okebu communities and is a rival of Codeco ("Cooperative for the Development of Congo"), a several thousand-strong militia who say their mission is to protect the Lendu tribe from the Hema and their allies.
After a relatively quiet decade, inter-ethnic unrest resumed in late 2017, resulting in the deaths of thousands of civilians with more than a million fleeing.
A previous conflict between rival militias had left thousands dead between 1999 and 2003 prior to intervention by a European peacekeeping force.
"We are here today committed and ready to join the peace process" and participate in a community integration programme to be led by Congolese authorities, group spokesman Jean-Marie Ngadjole said.
He added the group was committed to ensuring free movement of people and their goods across all communities and urged authorities to "facilitate the release of all" of its imprisoned members.
General Chalwe Munkutu Ngwashi, Ituri's deputy governor, said he "took note" of the group's commitment and urged "mutual forgiveness" and "reconciliation."
But he also urged "let's also disarm our hearts."
No date has been set for the group's disarmament and there have been similar agreements struck with other groups, including Codeco, though the effect on the ground has been minimal with violence continuing.
DRC Self-Defence Group Declares Unilateral 'Peace Accord'
FILE - Congolese Defense Forces soldiers remove the bodies of victims of an attack near the town of Oicha, 30 kms from Beni, DRC, on July 23, 2021. Over 30 were killed by the militia groups CODECO and the Allied Democratic Forces, which is allied to the Islamic State group.
BUNIA, DR Congo -Hundreds of members of a self-styled community self-defence group presented themselves to the Congolese army Monday and signed a unilateral "peace accord" in violence-plagued northeastern DR Congo, an AFP journalist said.