Da Silva, commonly known as Lula, took 50.9% of the second round vote to incumbent Jair Bolsonaro's 49.1%, according to Brazil's election authority.
watch nowLula used his victory address to pledge to combat climate change and deforestation — issues observers say have not just been sidelined but severely worsened under Bolsonaro's tenure.
In 2019, he told foreign journalists: "No country in the world has the moral right to talk about the Amazon.
"Around 95% of deforestation in the last four years in the Amazon has had some level of illegality," he said.
Norway is already looking to resume aid for anti-deforestation efforts to Brazil, which it suspended during Bolsonaro's term, local newspaper Aftenposten reported Monday.