Obiang - heading a coalition of 10 parties that includes the ruling Democratic Party of Equatorial Guinea - said: "We are a benchmark in democratic terms."
The results announced by the National Election Commission showed the 73-year-old's two closest rivals - Bonaventura Monsuy Asumu and Avelino Mocache Mehengap - trailing with 1.5 percent each in Sunday's vote.
The Democratic Opposition Front (FOD) coalition of dissident groups boycotted the vote.
Turnout in the oil-rich west African country was also 93.7 percent. Commission chief Clemente Engonga admitted to anomalies in some of the results, with the number of votes cast in some areas exceeding the number of registered voters.
The results are subject to confirmation on May 2 by the constitutional court.
Seven candidates ran for the top job but Obiang was not seriously expected to be challenged.
He is Africa's longest-serving leader, after ousting his uncle Francisco Macias Nguema in 1979 and having him shot by firing squad.
Complaints of fraud
"These were the worst elections ever organised in this country," rival Asumu said, claiming that the vote had been marked by widespread fraud. Running for the fourth time, he said he had visited polling stations without ballot slips on polling day.
Another unsuccessful candidate, Gabriel Nse Obiang Obono, told AFP on Tuesday that he and 200 of his supporters had been barred from leaving his residence in the capital Malabo since the previous Friday.
Obiang's regime has frequently come under fire from human rights groups for suppressing dissident voices and the media, as well as for widespread corruption.
With territory divided between the African mainland and islands in the Gulf of Guinea, Equatorial Guinea boasts the highest GDP per capita in Africa thanks to its extensive oil and gas reserves - with oil revenues accounting for over 70 percent of national income. But the country ranks 144 out of 187 states listed on the United Nations' 2014 Human Development Index.
jbh/gsw (AFP, Reuters, AP)