The country's air force confirmed the 73-year-old flew to the Maldives with his wife and two security officials.
Sri Lanka's President Gotabaya Rajapaksa has fled the country ahead of his expected resignation as President.
The President fled on a military jet, amid mass protests over the island's economic crisis, BBC News reports.
The country's air force confirmed the 73-year-old flew to the Maldives with his wife and two security officials.
In his absence, he has appointed Prime Minister Ranil Wickremesinghe as acting president.
Mr Wickremesinghe has declared a state of emergency and regional curfew in the western province.
Mr Rajapaksa's departure ends a family dynasty that has dominated Sri Lanka's politics for the past two decades.
The president had been in hiding after crowds stormed his residence on Saturday, and had pledged to resign on Wednesday 13 July.
A source told the BBC that Mr Rajapaksa will not remain in the Maldives and intends to travel on to a third country.
His brother, former Finance Minister Basil Rajapaksa, has also left Sri Lanka and is said to be heading to the US.
As Sri Lankans awoke to the news, thousands of people took to the streets of the capital, Colombo. Many gathered at Galle Face Green, the city's main protest site. Some listened to fiery speeches at a makeshift stage set up for ordinary people to take the mic.
Punctuated by cries of "Victory to the struggle", the rallying cry of the protest movement, speakers railed against a government and the leaders they feel have failed them.
Police fired tear gas to disperse a group of protesters near the prime minister's office, but they managed to storm the office and other state buildings.
In an earlier televised address, Prime Minister Wickremesinghe said he had ordered the military to do "whatever is necessary to restore order".
"We can't tear up our constitution. We can't allow fascists to take over. We must end this fascist threat to democracy," he said.
But many protesters say they will continue their demonstrations until both leaders have resigned from government.
Some demonstrators were furious about Mr Rajapaksa's departure, seeing a lack of accountability.
"We don't like it. We want to keep him. We want our money back! And we want to put all the Rajapaksas in an open prison where they can do farm work," said protester GP Nimal.
But 23-year-old university student Reshani Samarakoon told the BBC that the former president's exile offered "hope that in the future we can eventually become a developed country, economically and socially".
Sri Lankans blame President Rajapaksa's administration for their worst economic crisis in decades.
For months they have been struggling with daily power cuts and shortages of basics like fuel, food and medicines.
The leader, who enjoys immunity from prosecution while he is president, is believed to have wanted to flee abroad before stepping down to avoid the possibility of arrest by the new administration.
The Rajapaksa family has dominated Sri Lankan politics for two decades, and with strong backing from the Sinhala Buddhist majority, Gotabaya became president in 2019.
His departure is a remarkable victory for the protesters who came to the streets to express their anger against the mismanagement of the economy and the escalating cost of living.
The president's departure threatens a potential power vacuum in Sri Lanka, which needs a functioning government to help start digging it out of financial ruin.
Politicians from other parties have been talking about forming a new unity government but there is no sign they are near agreement yet. It's also not clear if the public would accept what they come up with.
Under the constitution, it's Prime Minister Wickremesinghe who should act in the president's stead if the latter resigns. The prime minister is considered the president's deputy in parliament.
However, Mr Wickremesinghe is also deeply unpopular. Protesters set fire to his private residence on Saturday - he and his family were not inside - and he said he would resign to make way for a unity government, but gave no date.