Incumbent President Daniel Noboa claimed a runaway victory in Ecuador's presidential election, after voters endorsed the young leader's "iron fist" approach to rampant cartel violence.

With over 90 percent of the votes counted, the National Election Council said Noboa had an unassailable 12-point lead over his leftist rival Luisa Gonzalez.

Official results showed Noboa with 56 percent of the vote, against Gonzalez's 44 percent – a far bigger winning margin than expected after a virtual tie in the first round.

Speaking to jubilant supporters in his hometown of Olon, the 37-year-old president claimed a "historic victory".

"A huge hug to all those Ecuadorians who always believed in this young president!" he said.

"Ecuadorians have spoken, from tomorrow morning we will go to work."

Gonzalez – seemingly shocked by her weak showing and perhaps the end of her dream of becoming Ecuador's first woman president – immediately questioned the results.

She accused Noboa of "the most grotesque electoral fraud" and called for a recount of the ballots.

"I refuse to believe that the people prefer lies over the truth," she said.

She did not immediately provide evidence for her claims of fraud. (AFP)