By Charles Haviland
BBC News, Colombo
Mr Rajapaksa, seen here with his wife, is riding high after the rebels' defeat
Sri Lanka will hold both presidential and parliamentary elections before April 2010, state radio says.
The holding of the presidential poll nearly two years ahead of schedule reflects the government's popularity.
The announcement comes five months after its military victory over Tamil Tiger rebels.
The move also comes three days after the coalition of President Mahinda Rajapaksa scored its eighth clear victory in provincial polls.
The coalition has now decided the decks are clear for elections by April.
Mr Rajapaksa, who is hugely popular among the Sinhalese majority, is likely to score a clear victory.
The opposition is weak and the president is hoping for a two-thirds majority which would enable him to change the constitution, possibly making provision for more than two successive presidential terms.
He has said that he will wait until after the vote to introduce political reforms aimed, for instance, at addressing Tamil grievances.
Mr Rajapaksa and other top politicians regularly speak of the need for reconciliation.
On Monday the president used the Tamil language to address newly-elected local politicians from the north and pledged to resettle displaced Tamils soon.
But his critics say he is being vague about concrete plans for reconciliation and about the nuts and bolts of reforms - for instance, the degree to which powers might be devolved to Tamil-majority areas.
Dayan Jayatilleka, recently sacked as Sri Lanka's ambassador to the UN in Geneva, writes in a new article that "there is no informed discussion about the nature of the post-war order".