President Mahinda Rajapakse said he saw the overwhelming majority for his United People's Freedom Alliance (UPFA) as a vote for his economic policies and the defeat of Tamil Tiger guerrillas in a major military offensive last year.
"This outstanding victory is an endorsement of the 'Mahinda Chintana' (Mahinda vision)," Rajapakse said in a statement on Friday night.
"I asked you for a strong parliament that can meet any challenge," he said. "I sincerely thank you for giving me an unprecedented majority that will help make Sri Lanka an example to the rest of the world."
The UPFA secured 117 seats in the 225-member assembly with another 45 seats still to be declared. The main opposition United National Party (UNP) was reduced to 46 seats.
UNP leader Ranil Wickremesinghe said the election campaign was marred by wide-spread abuse of state resources by the ruling party as well as misuse of state-run media for government propaganda.
"The government has a majority, but not a mandate to rule," Wickremesinghe told reporters in Colombo.He said the record low turnout of just over 55 percent compared to the national average of 75 percent for parliamentary elections showed that voters had lost faith in the system.
"For the first time, we have a parliament which has no mandate from the people," Wickremesinghe said adding that they will mount a campaign to agitate for democratic freedoms both in and outside parliament.
Rajapakse had been hoping for a two thirds majority that would allow him to alter the constitution, which currently limits presidents to two successive terms.
Police chief Mahinda Balasuriya appealed for calm and said victory celebrations should be peaceful.
Rajapakse called the vote ahead of schedule after his January re-election, which came in the wake of his defeat of Tamil Tiger rebels in May.
The man who led the military, former army chief Sarath Fonseka contested the election from his cell at the naval headquarters in Colombo where he is detained.
He won a seat representing part of Colombo, but his party did poorly, securing only five seats.
His wife, Anoma, told reporters in Colombo Saturday that the former four-star general will address parliament at its first sitting even though he is still in detention amid a court martial hearing.
"We can't accept this election as fair because our leader was locked up during the campaign and we faced an enormous amount of problems from the police and government authorities during campaigning," Fonseka said.
Opposition parties were largely united behind Fonseka in his campaign for the presidency in January, but lost cohesion after his arrest and went into the parliamentary election with little hope of victory.
Fonseka faces court martial proceedings for allegedly engaging in politics before retiring from the armed forces in November.
Fonseka and Rajapakse were the architects of the military campaign that defeated the Tamil Tigers at the end of a 37-year conflict that claimed up to 100,000 lives, according to UN figures.
However, the two fell out over who should take credit and Fonseka was arrested just weeks after losing the presidential vote.
For many Sri Lankans, it was the first legislative poll in which they could vote without fear of Tamil Tiger violence and suicide attacks.