Bashar al-Assad won 88.7% of the vote in Syria's presidential election, parliament speaker Mohammad al-Laham has said.
He secured a third term in office despite a raging civil war that grew out of protests against his rule.
Even before Mr al-Laham spoke, celebratory gunfire and fireworks erupted in Damascus in anticipation of the news.
Three people were killed in the capital and 10 were wounded by the gunfire, the Syrian Observatory for Human Rights monitoring group said.
Nearly an hour after the announcement, heavy shooting could still be heard, despite an appeal by the victorious Assad that "joy and enthusiasm" could not justify the danger caused by the celebratory fire.
State television showed crowds cheering and dancing in Damascus, Qamishli in the Kurdish northeast of the country, the Druze city of Suweida in the south and the contested city of Aleppo in the north.
Syria's constitutional court earlier said that turnout in yesterday's election and a previous round of voting for Syrian expatriates and refugees stood at 73%.
Mr Assad's foes have ridiculed the election, saying the two relatively unknown and state-approved challengers offered no real alternative to Assad.
Former minister Hassan al-Nouri got 4.3% of the vote while parliamentarian Maher Hajjar secured 3.2%, fewer than the number of spoilt ballots.
They also said that no credible poll could be held in the midst of a conflict that has killed 160,000 people, driven millions from their homes and put swaths of northern and eastern Syria beyond Assad's control.
"These elections are illegitimate and undermine the political efforts to find a solution to this horrific conflict," the European Union said in a statement.
The United States, which has repeatedly said President Assad lost his legitimacy when he responded with force to an outbreak of protests more than three years ago, said the vote changed nothing.
"With respect to the elections that took place, the so-called elections, the elections are non-elections, the elections are a great big zero," Secretary of State John Kerry said during a brief visit to neighbouring Lebanon.
"They are meaningless, and they are meaningless because youcan't have an election where millions of your people don't evenhave the ability to vote, where they don't have the ability tocontest the election, and they have no choice."
A coalition of Islamist rebel fighters described the vote as "Elections of Blood" and said it had no legitimacy.
Syrian officials had described the predicted victory as vindication of Assad's three-year campaign against the rebels and a landmark for democracy - the first time in half a century that Syria has held a contested presidential election.
For many Syrians voting yesterday, politics took second place to the yearning for stability and security after three devastating years of conflict which grew out of the mass protests in 2011 against Assad's rule.
For the country's minority Alawite, Christian and Druze communities, the Alawite president offers a bulwark against increasingly radical Sunni Muslim insurgents and the promise -however remote - of a return to stability.
The official figures also suggest that many of the majoritySunni Muslims turned out to vote for Assad, whether out ofweariness with the conflict or fear of retribution if they didnot vote.
Previous presidential votes had been referendums to approve the appointment of Bashar and his father, Hafez al-Assad, who ruled for 30 years until his death in 2000. Hafez never won less than 99%, while his son scored 97% in 2007.
It comes as a top UN official appealed to Syria to hand over urgently all remaining chemical agents after missing a deadline for their destruction, and urged Damascus' allies to intervene.
Under a UN-backed and US-Russia brokered deal agreed last year after the United States threatened air strikes against Syrian government targets, the weapons were to be destroyed by 30 June.
The deal was reached after a sarin nerve gas attack in a rebel-held Damascus suburb killed around 1,400 people.
But 7.2% of Syria's declared chemical agents, though packed, remain inside the country, Sigrid Kaag, the UN official overseeing the process, told reporters in New York.
UN chief Ban Ki-moon had already confirmed in a letter to the Security Council that the June deadline would not be met and Ms Kaag urged compliance as soon as possible.
She heads a joint mission by the United Nations and the Organization for the Prohibition of Chemical Weapons to disassemble the weapons.
Syria claims that the security situation is too dangerous on the ground for the agents to be transported safely by road to the port of Latakia.
Asked if Syria was stalling, Ms Kaag acknowledged security is a concern but warned: "It doesn't mean that additional delays can be incurred."
Danish and Norwegian ships are to take the chemicals from Latakia to a US ship for destruction at sea, as well as at sites in Finland, the US and Britain.
Western diplomats say the key question is how long the mission should continue.
They also await the outcome of a separate fact-finding mission into the regime's alleged ongoing use of chlorine gas.
The OPCW mission was dispatched after France and the US alleged government forces may have unleashed industrial chemicals on a rebel-held village earlier this month.
Syria did not have to declare its stockpile of chlorine - a weak toxic agent - as part of the disarmament deal as it is widely used for commercial and domestic purposes.
The secretary general has said he wants the mission to work for a "finite period" after June 30 to eliminate the chemical agents.
Ms Kaag said the mission would focus on "residual activities."