Shouts of joy erupted at the commission's offices as the results were announced early on Thursday morning, AFP journalists reported.
Careful statements by the worldwide community did not congratulate Tshisekedi but merely took note of the official results and urged peace and stability in a country with little of it. Observers appeared to be watching for how Fayulu's supporters reacted.
Fayulu can appeal the results to Congo's constitutional court but has not yet indicated whether he will.
After the 30 December vote, internet and text-messaging services were shut down nationwide in a move that the government said was necessary to guard against the spread of unofficial results. CENI has come under pressure from the DRC Catholic Church's National Episcopal Conference of the Congo (Conférence Épiscopale Nationale du Congo: CENCO), which mounted its own 40,000-strong electoral observer mission and parallel vote tabulation operation.
They would be deployed if needed to protect USA citizens and diplomatic facilities in DR Congo's capital, Kinshasa, he said.
"This is because a Tshisekedi presidency would be the least bad alternative to a Shadary victory for the regime as it would put a veil of legitimacy on the electoral process and would be more manageable than a Fayulu presidency", she said.
"How long are we going to negotiate results?" he asked.
Martin Fayulu: The ex-oil tycoon - worked for Exxon Mobil for 20 years and entered politics in 2006.
Many Congolese objected to Shadary, suspecting that Kabila would continue to rule from behind the scenes.
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"We must have clarity on these results, which are the opposite of what we expected, " Le Drian told CNews. Belgian Foreign Minister Didier Reynders said his country planned to raise concerns at the U.N. Security Council.
Main opposition leader Felix Tshisekedi was Thursday named the provisional victor in Kinshasa after a delayed count.
The delayed results, 10 days after the December 30 vote, came after global pressure to announce an outcome that reflected the will of the people, with the USA threatening sanctions. He was a vocal activist during the two-year delay in Congo's election, insisting it was time for Kabila to go.
Among the challenges he would face is an Ebola outbreak in the east of the country. He claims that he won a majority of the votes and that he was deprived of victory because a deal was made with Tshisekedi.
Western pressure likely has little effect, however, as Congo's government has rejected what it calls interference and expelled the European Union ambassador days before the vote.
"That is why I follow it directly with - and I know many of you find it hard to accept - but I say it with sincerity, I pay homage to President Joseph Kabila, President of the Republic".
Kabila has ruled since 2001 in the troubled nation rich in the minerals key to smartphones around the world. He is barred from serving three consecutive terms, but until he announced past year that he would step aside many Congolese feared he'd find a way to stay in office.
Tshisekedi inherited the leadership of the UDPS party when his father, Etienne, died in 2017.
Fellow opposition candidate Fayulu who was backed by former Katanga governor Moise Katumbi - considered a traitor by Kabila - and ex-warlord and former vice president Jean-Pierre Bemba, had also sounded a conciliatory tone.
Antonio Guterres, the United Nations secretary general, said he "takes note" of the announcement and urged all parties to "refrain from violence and ... to channel any electoral disputes through the established institutional mechanisms".