His main challenger Samura Kamara came second with 41.16% of the vote, according to final results announced in Freetown by commission chief Mohamed Kenewui Konneh.
Vote tallying had already been disputed by the opposition All People's Congress (APC), which condemned in a statement Monday an alleged lack of inclusiveness, transparency and responsibility by the electoral commission.
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Sierra Leone’s Opposition APC Rejects Partial Election Result
The party pointed to the lack of information about which polling stations or districts the ballots were coming from.
It had said it "will not accept these fake and cooked up results."
In a follow-up statement, it alleged "overvoting" in some areas and said the party "continues to reject" the "fabricated results" and "reaffirms our victory."
During a Monday evening press conference, European Union observers said a lack of transparency and communication by the electoral authority had led to mistrust in the electoral process.
The monitors said they witnessed violence at seven polling stations during voting hours and at three others during the closing and counting stages.