The ex-president returned to Sri Lanka on a Singapore Airlines flight. He travelled from Thailand to Singapore to take the flight as there are no direct flights between Bangkok and Colombo, sources said.
Wickremesinghe, who took over as the Acting President after his predecessor Gotabaya Rajapksa fled the country and resigned last week, is the first Sri Lankan president to be elected by Parliament following a vote.
The Parliament would be summoned on Saturday (July 16) to take nominations for the next President and then to have an election among 225 MPs.
On Saturday, Rajapaksa had announced to step down on July 13 after thousands of protesters stormed his official residence, blaming him for the unprecedented economic crisis that has brought the country to its knees.
President Rajapaksa is accompanied by his wife and two security officials who flew with him from Colombo on a Saudi Airlines plane.
The bank, CBSL, said in a notice that the public is "warned of the possible exposure to significant financial, operational, legal and security related risks as well as customer protection concerns posed to the users by investments in Virtual Currencies (VCs)".
The protesters had been provided some 15 minutes to convey their side of the story to the viewers, after which the channel suspended transmission.
He said the vote for the new president will take place on July 20 and urged citizens to remain calm.
The resignation letter of the President was signed and handed over to a senior government official who will hand it over to the Parliament Speaker.
A couple of days after Mahinda Rajapaksa resigned as Sri Lankan Prime Minister, his brother and President Gotabaya Rajapaksa on Wednesday said he will appoint a new Prime Minister and cabinet this week.
Meanwhile, President Gotabaya and Prime Minister Mahinda have appealed to the people to exercise restraint and remember that violence only begets violence, saying the economic crisis needs an economic solution which his government is committed to resolving.
Rajapaksa had declared emergency on April 1 also after a mass protest opposite his private residence. He had revoked it on April 5.
Sajith Premadasa Opposition leader and leader of the Samagi Jana Balawegaya or United People's Force handed over two motions to the Speaker Mahinda Yapa Abeywardena who is to announce their future cause in Parliament on Wednesday.
Rajapaksa also justified the public anger over the unbearable cost of living, but refused to give up his post despite mounting public pressure around the country with massive protests demanding him to step down.
People have been facing hardships since last year when the prices of fuel began to go up, scheduled power cuts were announced by the government and the prices of good began inching up.