The agreement marks a breakthrough in talks held by the administration of US President Donald Trump, which also aim to attract billions of dollars of investment to a region rich in tantalum, gold, cobalt, copper, lithium and other minerals.
At a ceremony with US Secretary of State Marco Rubio at the Department of State, the two countries' foreign ministers signed the agreement pledging to implement a 2024 deal that would have Rwandan troops withdrawing from eastern DR Congo within 90 days, according to a version initialled by technical teams last week and seen by Reuters.
The two countries will also launch a regional economic integration framework within 90 days, the agreement said.
"They were going at it for many years, and with machetes - it is one of the worst, one of the worst wars that anyone has ever seen. And I just happened to have somebody that was able to get it settled," Trump said on Friday, ahead of the two sides signing the deal.
"We're getting, for the United States, a lot of the mineral rights from the Congo as part of it. They're so honored to be here. They never thought they'd be coming."
Trump was due to meet the foreign ministers in the Oval Office later on Friday.
Rwanda has sent at least 7000 soldiers over the border, according to analysts and diplomats, in support of the M23 rebels, who seized eastern DR Congo's two largest cities and lucrative mining areas in a lightning advance earlier this year.
The gains this year by M23, the latest cycle in a decades-old conflict with roots in the 1994 Rwandan genocide, sparked fears of a wider war drawing in DR Congo's neighbours.
Rwandan Foreign Minister Olivier Nduhungirehe called the deal a turning point.Â
DR Congo Foreign Minister Therese Kayikwamba Wagner said the agreement must be followed by disengagement.
The US State Department did not immediately respond to a request for comment on the initialled version of the agreement.
Massad Boulos, Trump's senior adviser for Africa, told Reuters in May that the US wanted the peace deal and accompanying minerals deals to be signed simultaneously this year.
However, the agreement signed on Friday gives DR Congo and Rwanda three months to launch a framework "to expand foreign trade and investment derived from regional critical mineral supply chains," according to the initialled version seen by Reuters.
A source familiar with the matter told Reuters on Friday that another agreement on the framework would be signed by the heads of state at a separate White House event at an unspecified time.
There is an understanding that progress in ongoing talks in Qatar - a separate but parallel mediation effort with delegations from the DR Congolese government and M23 - is essential before the signing of the economic framework, the source said.
The agreement signed on Friday was set to voice "full support" for the Qatar-hosted talks, according to the initialled version.
It also says DR Congo and Rwanda will form a joint security co-ordination mechanism within 30 days and implement a plan agreed last year to monitor and verify the withdrawal of Rwandan soldiers within three months.
DR Congolese military operations targeting the Democratic Forces for the Liberation of Rwanda, a DR Congo-based armed group that includes remnants of Rwanda's former army and militias that carried out the 1994 genocide, are meant to conclude over the same timeframe.
Rwanda has long denied helping M23, saying its forces are acting in self-defence against DR Congo's army and ethnic Hutu militiamen linked to the 1994 Rwandan genocide.
"This is the best chance we have at a peace process for the moment despite all the challenges and flaws," said Jason Stearns, a political scientist at Simon Fraser University, specialising in Africa's Great Lakes region.
Similar formulas have been attempted before, he added, and "it will be up to the US as they are the godfather of this deal, to make sure both sides abide by the terms."
