Wickremesinghe faces the task of leading the country out of its economic collapse and restoring public order after months of mass protests, BBC reported.
He roundly defeated his main rival for the job, Dullus Alahapperuma, with 134 votes to 82 in the parliamentary vote.
Sri Lanka's ex-president Gotabaya Rajapaksa fled the country last week.
He bolted to the Maldives and then Singapore after thousands of protesters stormed his presidential residences and other government buildings, calling for his resignation.
They had also called for the resignation of Wickremesinghe, who was appointed prime minister in May. Protesters burnt down his private home and also stormed his prime ministerial office in Colombo in demonstrations against his leadership.
Sri Lanka is effectively bankrupt and facing acute shortages of food, fuel and other basic supplies.
After his election, Wickremesinghe told parliament the nation was "in a very difficult situation" adding there were "big challenges ahead".
RHM/PR