"The CBF (Brazilian Football Confederation) and Brazilian football mourn the death of one of its greatest legends, Mario Jorge Lobo Zagallo. The CBF offers solidarity to his family and fans in this moment of grief," CBF President Ednaldo Rodrigues said in a statement.
Rodrigues added that there will be seven days of mourning and a minute's silence will be observed ahead of all matches this weekend.
Zagallo was admitted into a Rio de Janeiro hospital at the end of December.
The Brazilian football legend won four FIFA World Cup trophies. He was the first person to win the world title both as a player and coach.
Franz Beckenbauer for Germany and Didier Deschamps for France achieved it after Zagallo.
FIFA President Gianni Infantino paid tribute to Zagallo, as he received "with great sadness" the death of the icon, who he described as "a man whose impact on the FIFA World Cup is unparalleled."
"He will be remembered as the Godfather of Brazilian football and his presence will be sorely missed by everyone in the game but especially here at FIFA.
"The story of the FIFA World Cup cannot be told without Mario Zagallo. I wish to send my heartfelt condolences to the country of Brazil, the Brazilian Football Association and to his family and friends," Infantino said on FIFA website.
Zagallo, a former Brazil winger, won consecutive World Cups in 1958 and 1962 as a player.
He was the head coach of Brazil when the national team won the 1970 World Cup.
Zagallo was Brazil head coach Carlo Alberto Parreira's assistant for the 1994 World Cup held in the US where the Brazilians beat Italy on penalties to be the world champions.
For the 1998 World Cup, he was named Brazil's head coach once again but Zagallo's men lost the final to France 3-0 in Paris.
