The country's National Electoral Council says there was no indication of fraud in Sunday's elections but Moreno's conservative opponent Guillermo Lasso insists the vote was marred by fraud.
The head of Ecuador's National Electoral Council announced on Tuesday that ruling Socialist party candidate Lenin Moreno has won the country's presidential election.
The announcement came after Moreno's conservative challenger Guillermo Lasso refused to recognise the results of Sunday's election, demanding a recount. He also called his supporters to fill the streets to guard against fraud.
Electoral council president Juan Pablo Pozo said, the results are "irreversible," adding there was no indication of fraud.
"Ecuador has chosen freely," he said in a televised speech.
Moreno garnered 51.16 percent of the votes, compared with Lasso's 48.84 percent, with over 99.65 percent of votes counted, the council said.
However, Lasso refused back down saying he would challenge the results as his supporters protested the election results in the Andean capital Quito on Tuesday.
The Organization of American States, which had an observer mission in Ecuador, said on Monday it had seen "no discrepancies" between results collected by its observers at polling stations and official results.