If the legislative result is confirmed, the win for pro-Kabila lawmakers will put them in control of parliament for the next five years.
Provisional results released earlier by the elections committee had also indicated that the pro-Kabila FCC coalition had secured a majority, but by a fewer number of seats.
It means the next prime minister will be chosen from among forces loyal to Kabila.
International observers have been closely watching developments in sub-Saharan Africa’s largest country, which covers an area equivalent to that of western Europe, with reactions to the election outcome guarded.
Most leaders called for any disagreements to be resolved peacefully in statements that pointedly lacked any congratulations for Tshisekedi, with the dispute over the results playing out in the UN Security Council on Friday.
Addressing the Council by video conference, election chief Nangaa pleaded for “the new authorities to be supported by the international community”.
But Bishop Marcel Utembi, head of CENCO, which represents DR Congo’s Catholic bishops, urged the Security Council to ask the election committee to release data on the counting at polling stations to allow for verification.
Analysts said it was likely Kabila had struck a deal with the 55-year-old opposition chief to avoid a violent backlash and the international condemnation that would have followed if Shadary had been declared winner.
In turn, Kabila — who has ruled the country with an iron fist since 2001 — was likely to seek immunity from prosecution and protection for his family’s business assets.