With 42 percent of the ballots from the Sunday election counted, the electoral office said that Fujimori had 52.9 percent, while her rival, leftist candidate Pedro Castillo is trailing behind with 47.1 percent.
Earlier, America TV and IPSOS exit poll data showed that Fujimori had 50.3 percent of the votes, while Castillo got 49.7 percent.
Peru held a presidential election runoff as none of the candidates managed to get a minimum of half plus one of the votes required for victory in the first round.