Appearing on live television, the far-right president said he took a coronavirus test Monday after developing symptoms, including a high temperature.
"I didn't know what would be the result. But finally it was positive," Bolsonaro told reporters speaking from the presidential residence in Brasilia Tuesday.
"There is no reason for fear. That's life. Life goes on. I do thank God for my life and the role I have received to decide the future of this great nation that is called Brazil," he said.
Brazil's leader has been criticized at home and abroad for his lax response to the coronavirus pandemic, dismissing it as a "little cold" at the onset of the crisis.
"I was not surprised [by the coronavirus test result]," Bolsonaro said Tuesday. "I am president of the Republic; I am at the front line of the combat."
In late June, a federal judge ordered the president of South America's largest country to wear a face covering while in public or receive a fine of nearly $400 a day. The decision came after the president repeatedly appeared in public without a mask.
Despite the court order, Bolsonaro has since attended several public events without a mask, appearing at a July 4th celebration at the American Embassy without a face covering this weekend. The president was also photographed with the U.S. Ambassador to Brazil Todd Chapman at the event.
With coronavirus-related deaths topping 65,000 in Brazil, Bolsonaro has lost many high-profiles supporters and has faced governmental resignations since the outbreak worsened in the country.
The president fired one of the health ministers for supporting restrictions imposed by regional governors, as Bolsonaro publicly undermined them and rallied his supporters to disobey them.
A second health minister resigned after openly disagreeing with Bolsonaro over chloroquine, an anti-malarial drug related to hydroxychloroquine.
The president's diagnosis comes a day after his son accused those criticizing his father's response to COVID-19 of wishing Bolsonaro's death.
"The immense number of people rooting for the death of the head of the executive right now should trigger an immediate show of solidarity from other [political] leaders," Carlos Bolsonaro wrote in a tweet Monday night.
As of Tuesday, Brazil has over 1.6 million coronavirus cases, according to the Johns Hopkins Coronavirus Resource Center.
The president has been tested three times before for COVID-19, all of which he said have come back negative.
ABC News' Aicha El Hammar contributed to this report.
This report was featured in the Wednesday, July 8, 2020, episode of “Start Here,” ABC News’ daily news podcast.
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