Opposition leader Felix Tshisekedi pulled a surprise win against Kabila’s favourite candidate Emmanuel Ramazani Shadary after garnering 7 million votes, or 38 percent of December 30th presidential election.
Congo electoral commission made the announcement early Thursday morning.
"Some observers have suggested that President Joseph Kabila's government sought to make a deal as hopes faded for a win for Shadary," the Associated Press reported.
Tshisekedi, who is the son of Congo's historic opposition leader, Etienne Tshisekedi, who died in 2017, outpaced another opposition frontrunner, Martin Fayulu, who came in second with more than 6 million votes while the governing coalition's candidate Emmanuel Ramazani Shadary came in third with more than 4 million votes.
However, all is not yet clear for Tshisekedi. There are serious concerns of unrest if people conclude that results have lacked in credibility.
The Catholic Church, who had the largest number of election observers deployed, has warned they will reject any results they believe to be fraudulent.
"The influential Catholic Bishop's Conference, which fielded 40,000 observers, says the outcome of the much-anticipated vote is at odds with its tally. Last week the bishops said their observations showed a clear winner – although they did not name Martin Fayulu, the other opposition frontrunner – as that candidate. So Tshisekedi's apparent victory may become subject to a legal challenge and protests," Reported National Public Radio’s Ofeibea Quist-Arcton from Kinshasa.
The election outcome was initially expected to be announced on Sunday and the interim result can still be challenged.
Mr Fayulu, a former oil tycoon, dismissed the results as "a true electoral coup", telling Radio France Internationale they had "nothing to do with the truth of the ballot box".
In recent days, rumours of a deal between Mr. Tshisekedi and Mr. Kabila have emerged worrying other members of the opposition. Mr Tshisekedi himself has acknowledged talks with the ruling party to prepare a transition of power but denies there has been any kind of deal.
Speaking to thousands of cheering supporters in Kinshasa, Tshisekedi paid his respects to Kabila, whom he described as "an important political partner".
"He said he is will to be a president for all the people of Congo and thanked Fayulu and Shadary, saying he is willing to work with them to build a better Congo," Al Jazeera's Haru Mutasa, reporting from Kinshasa, said.
After decades of unsuccessfully trying to clinch power, this is an historic moment for Mr Tshisekedi's party, the Union for Democracy and Social Progress (UDPS).
Mr. Tshisekedi has promised to make the fight against poverty his priority.
If everything goes smoothly, this will be the first time DR Congo enjoys a peaceful transfer of power since the country's independence from Belgium in 1960.
President Joseph Kabila who is stepping down after 18 years in office has promised to peacefully and orderly transfer power.
Mr. Kabila was barred from running for another term under the constitution, and was supposed to step down two years ago, but the election was postponed after the electoral commission said it needed more time to register voters.