Alassane Ouattara has won a controversial third term in office in an election boycotted by the opposition.
He took 94% of the vote, even winning 99% in some of his strongholds.
Turnout was put at almost 54%. The result has to be confirmed by the Constitutional Council.
On Monday, the Ivorian opposition said it was creating a transitional government which would organise a new election.
Main opposition candidates Pascal Affi N’Guessan and Henri Konan Bédié had urged their supporters not to vote in Saturday’s poll.
They got 1% and 2% respectively, while a fourth candidate, Kouadio Konan Bertin, also got 2%, according to the official results.
Opposition figures say it was illegal for Mr Ouattara to stand for a third term as it broke rules on term limits.
“Maintaining Mr Ouattara as head of state is likely to lead to civil war,” M N’guessan said, adding that the opposition noted a vacancy of power.
But the president’s supporters dispute this, citing a constitutional change in 2016 which they say means his first term effectively did not count.
His party has warned the opposition against any “attempt to destabilize” the country, which is still recovering from a civil war sparked by a disputed election in 2010.
It has accused the opposition of sedition by calling for a transitional government.
The European Union has said it was deeply concerned about tensions in the country – its foreign policy chief Josep Borrell said incitements to hatred were continuing.
The United Nations refugee agency has said thousands of people have fled to neighbouring countries, fearing more violence.
At least 35 people have been killed in political clashes, which continued on election day.