The provisional election results released late Thursday mean that the landlocked central African nation avoids a runoff. More than a dozen candidates had challenged Deby, who came to power in a 1990 military coup.
The Electoral Commission said 76 percent of more than 6 million registered voters turned out for the April 10 poll.
Earlier this week, the opposition had withdrawn from the electoral commission, citing doubts that the vote would be credible.
Deby told hundreds of supporters in the capital, Ndjamena, that the win was “your victory.” The result still needs to be ratified by Chad’s Constitutional Council.
Strategic location
Chad is the base for France’s military operations in Africa and headquarters for a five-nation regional force intended to curb Islamist extremists groups, such as Boko Haram, which operates from northeastern Nigeria.
Chad was visited on Wednesday by the US envoy to the United Nations, Samantha Power, and top US military officials.
The Associated Press reported that Power expressed displeasure over a government decision to shut down the internet and text messaging through Chad for several days during the election.
In a rare appearance before foreign journalists, Deby denied opposition claims that some 60 security force personnel who had voted against him had disappeared.