The leftist president received 51.7 percent of the vote, compared with 48.2 percent for right-wing candidate Flávio Bolsonaro, according to official figures. Lula has thus secured a fourth term as president.
Polling stations stayed open two hours longer than planned, and both Lula and Bolsonaro requested that polling stations extend their opening hours.
The candidates have starkly opposing views on most issues, from climate change and social welfare to relations with the United States. Flávio Bolsonaro is the son of imprisoned former president Jair Bolsonaro.
In the first round of the election on October 4, Lula received just over 45 percent of the vote, while Bolsonaro received 47 percent. Since neither candidate received more than 50 percent, the election went to a second round.
