"The definitive results of the vote find in our favor once more," Obiang's son, Vice President Teodoro Nguema Obiang Mangue, wrote on Twitter.
"We will continue to prove that we are a great political party."
Obiang, 80, who seized power in a 1979 coup, is the longest-ruling head of state in the world excluding monarchs. He has never officially been re-elected with less than 93 percent of the vote.
Electoral commission head Faustino Ndong Esono Eyang confirmed that Obiang would serve another seven years in the top job. The commission said the turnout rate for the election was 98 percent.
The landslide result was widely expected in the oil-rich and authoritarian Central African nation, where the political opposition is extremely weak.
Obiang had the backing of a coalition of 15 parties, including his all-powerful ruling Democratic Party of Equatorial Guinea (PDGE).
The PDGE, which was the country's only legal political movement until 1991, also swept all seats in the National Assembly and the Senate.
The percentages won by the opposition candidates, Andres Esono Ondo of the Convergence for Social Democracy and Buenaventura Monsuy Asumu of the Social Democratic Coalition Party, were not announced, with both garnering just a few thousand votes.
Obiang has ruled Equatorial Guinea for more than 43 years after ousting his uncle, Francisco Macias Nguema.