"We announce an official three-day mourning in the country in memory of the 61 victims of the tragic accident in Vinhedo," the leader wrote on X.
The decree enters into force from the moment of publication, the document said.
The plane with 57 passengers and four crew members fell on one of the residential areas of the town of Vinhedo on Friday, killing everyone on board. No one on the ground was injured. The cause of the crash was not immediately named.
Russian President Vladimir Putin sent condolences to Brazilian President Luiz Inacio Lula da Silva on Saturday following the crash of the regional passenger plane.
"Please accept my deepest condolences in connection with the tragic consequences of a passenger plane crash in the state of Sao Paulo. We share the grief of the friendly people of Brazil," the letter of condolences published by the Kremlin read.
Putin asked the Brazilian leader to "convey words of sincere sympathy and support to all those who lost their family members and friends in this air disaster."