The referendum held on December 18-19 resulted in a "yes" vote of 84.31% with 15.69% voting "no", electoral results released late on Wednesday showed.
Apollinaire Malu Malu, the electoral commission chief, put the turnout at 61.97%.
The results were to be sent to the supreme court for validation, within 48 hours if they were uncontested or within two weeks if problems were raised.
Earlier on Wednesday, the supreme court rejected opposition complaints about the referendum. It ruled that the complaints, calling for the vote to be annulled and held again, were inadmissible because the electoral commission had not yet published the provisional results of the referendum.
Supporters of Father Theodore Ngoy, an opposition leader and "no" advocate who was arrested after the referendum, said they would refile their complaints once the results were in.
About 15 million of Congo's 25 million registered voters cast ballots in the referendum at 40,000 polling stations in the Europe-sized country, Malu Malu said.
He said that minor irregularities had been reported, but said the poll was fair overall.
The charter grants greater autonomy to mineral-rich provinces and lowers the minimum age for presidential candidates from 35 to 30, allowing an election bid by 34-year-old Joseph Kabila, who has ruled as president since his father was assassinated in 2001.
The charter is considered crucial
to securing peace in Congo
The constitution opens the way for the first democratic presidential and parliamentary elections in the central African country in more than 45 years. Both elections are due in March, but no specific date has been set.
The new charter is also considered crucial to securing peace after two wars, the first in 1996-1997 and another from 1998-2002 that drew in the armies of six African nations.
It also aims to decentralize authority, dividing the vast nation into 25 semiautonomous provinces drawn along ethnic and cultural lines.