Official final results were not due for another three hours, but polling showed the incumbent with a powerful lead over his chief opponent, former army commander General Sarath Fonseka.
The two war victors turned to foes in a bloody campaign that culminated in a largely peaceful election on Tuesday, with turnout that independent observers placed at between 70 and 80 percent of the Indian Ocean island's 14 million registered voters.
Fonseka, a political neophyte, delivered an election day shock by admitting he was not registered to vote, after saying he may have done so but did not want to say where for security reasons.
The winner will take the reins of a $40 billion economy which has enjoyed a partial peace dividend, and is on the path to recovery with big Chinese and Indian investments into infrastructure and plans to put $4 billion into development.