Representatives of both sides signed a declaration of principles on Saturday, a copy of which was obtained by Reuters, agreeing to an August 18 deadline.
The ceremony followed months of Qatari mediation since talks began in April.
The United States, which has hosted separate talks between the governments of Congo and Rwanda, has exerted pressure to finalise a durable peace deal in Congo.
President Donald Trump has made clear he hopes that will spur Western investment in a country rich in tantalum, gold, cobalt, copper, lithium and other minerals.
The Rwandan and Congolese foreign ministers signed a peace deal in June and met with US President Donald Trump at the White House.
Trump had invited Congolese President Felix Tshisekedi and Rwandan President Paul Kagame to Washington at the time to sign a package of agreements, potentially including economic deals.
The rebel group M23 has controlled eastern Congo's largest city, Goma, since late January - the latest in a series of uprisings - and made gains across North Kivu and South Kivu provinces.
Rwanda has long denied allegations it has helped M23, which has seized more territory in Congo than it ever previously held.
The fighting has killed thousands and displaced hundreds of thousands more this year, while escalating the risk of a full-scale regional war.
Several of Congo's neighbours had troops deployed in eastern Congo when the advance began.
Qatar's Minister of State for Foreign Affairs Mohammed bin Abdulaziz Al-Khulaifi told reporters Saturday's declaration "lays the groundwork for a new phase of partnership among the various components of society in the Democratic Republic of the Congo - including armed movements that have chosen to prioritise the greater national interest".
The declaration was brought about by talks that followed a surprise meeting between Congolese leader Tshisekedi and his Rwandan counterpart Kagame, brokered by Qatar in March, during which they called for an "immediate and unconditional" ceasefire.
Congo had previously rejected the idea of holding talks with M23, branding it a terrorist group.
While denying it has supported M23, Rwanda has said its forces have acted in self-defence against Congo's army and ethnic Hutu militiamen linked to the 1994 Rwandan genocide.
Sources in both delegations have expressed frustration with the pace of negotiations in Doha and the lack of progress on confidence-building measures including the release of M23 members held by Congo and the re-opening of banks in rebel-held territory.
The declaration of principles does not resolve those issues, instead committing the parties to "creating the necessary conditions" to eventually do so.
It also does not address bigger questions concerning the possible Rwandan and M23 withdrawals from eastern Congo.
It says Congo and M23 agree that state authority should be restored "on all national territories" as part of an eventual peace agreement but does not elaborate.
The declaration "takes into account the red lines we have always defended, including the non-negotiable withdrawal" of M23, Congo government spokesman Patrick Muyaya said in a post on X on Saturday.
Negotiations for a peace agreement are to start no later than August 8, according to the declaration, which would give the parties less than two weeks to finalise a deal if they stick to their new August 18 deadline.
"We are confident and we are hopeful," Massad Boulos, Trump's senior adviser for Africa, told Reuters after Saturday's ceremony in Doha, adding Tshiskedi and Kagame "have both committed to resolving this".
