Saturday’s move came as a welcome surprise to observers as it signals a possible stabilisation in the Great Lakes region.
"We have decided to put down guns. War is not the best solution," Paul Rwarakabije, military commander of the Kinshasa-based Democratic Liberation Forces of Rwanda (FDLR), said on arrival at Kigali airport with several rebel colleagues.
"We have now decided that we can use peaceful means to solve any outstanding issues," he added, after Rwandan army officers greeted him with smiles and hugs.
Later, Rwanda army chief of staff Major General James Kaberebe told reporters Rwanda would now try to secure the return of his fighters "in the shortest time possible" from bases in neighbouring Democratic Republic of the Congo (DRC).
"This is a very important moment for Rwanda," said Kaberebe. "This is an initiative between the government of Rwanda and him alone. This does not involve the UN or the Kinshasa government."
"We have decided to put down guns. War is not the best solution"
Paul Rwarakabije, FDLR
"The people we have been fighting with have made a decisive decision to come back in peace and abandon fighting. This is very interesting and very welcome," he said.
Terms not released
No immediate indication was given of any negotiated terms for Rwarakabije's return.
The largely Rwandan Hutu FDLR is estimated by analysts to have between 15,000 and 20,000 fighters trying to topple the Tutsi-led Rwandan government from jungle bases in the east of the DRC.
Many FDLR fighters are Hutus implicated in the 1994 Rwandan genocide, although Rwarakabije, a former Rwandan army officer, has not been accused of a role in the orchestrated slaughter by Hutu extremists of 800,000 minority Tutsis and moderate Hutus.
A senior official of the UN peacekeeping mission in the DRC described Rwarakabije's surrender as "potentially very, very significant because if this results in the collapse of the FDLR command structure then it could be a huge development."
"This is a very important moment for Rwanda." This is an initiative between the government of Rwanda and him alone. This does not involve the UN or the Kinshasa government."
Major General James Kaberebe
Rwandan army chief of staff
The DRC government banned the political activities of the FDLR in September 2002 and told its leaders to leave the country as part of a pact aimed at ending the DRC's many-sided conflict.
The South African-mediated accord was one of a series of deals meant to end Congo's subsiding conflict, in which an estimated three million people died and Rwanda and Uganda were pitted against the DRC government.
Rwanda pulled out an estimated 20,000 troops from DRC last year and in return Kinshasa said it would disarm the Hutu fighters who fled to Congo soon after the genocide.
A new transitional DRC administration grouping government and former rebels was sworn in, in July, though fighting still rages in the east between an array of armed factions.