Deby, who has ruled the oil-producing central African state since a 1990 coup, won 88.66 percent of the votes in the April 25 poll, the head of Chad’s election commission told a news conference. He said voter turnout was more than 64 percent.
The outcome gives Deby a new five-year mandate and was widely expected after the three top opposition candidates withdrew from the race and called for a boycott over concerns the poll would be fixed.
One of the three, Abdelkader Wadal Kamougue, died on Monday at the age of 72, hours before the results were released.
“This is no shock. We knew Deby would win,” Djimrasnagar Ahmat, a resident in the capital N’Djamena, said after the results were announced.
“That’s why nobody was interested in this election. You will see that people didn’t even watch the results on television.”
A spokesman for Deby said the 64 percent turnout was proof that the opposition boycott call was unheeded, but opposition officials disputed the figure.
Election observers from the African Union and a central African mission said they believed turnout was below the 51 percent level hit during legislative polls in February, but did not give any further details.
Chad produces about 115,000 barrels of oil a day, but remains one of the poorest countries in the world.
Deby has spent much of the time since his last win in 2006 tackling a rebellion in the east.
In 2008 he faced a rebel barrage on the capital that killed hundreds, but he has since made peace with Sudan, ending what analysts said was a proxy war fought by each country’s rebels.
Deby has signed two infrastructure deals with China in recent months, including a $7.5 billion agreement with engineering firm CCECC to build 1,344 km (835 miles) of railway.