Felix Mieli Venerando played in all six of Brazil's matches in the 1970 tournament, making several key saves for a team that many consider the greatest of all time.
Some fans considered him the weak link in the team.
However, his team-mates stressed he was an key member of the squad and pointed to a save from England's Francis Lee in Brazil's narrow 1-0 win in the group stage as one of the crucial moments in the tournament.
"We won that game because of the save from Felix," captain Carlos Alberto told Radio ESPN. "Without him we wouldn't have won the competition."
Quiet, unassuming and popular with his team mates, Felix played for Brazil's Juventus, Portuguesa and Nacional in Sao Paulo, but he made his name after moving to Fluminense in 1968.
"Supporters should be eternally grateful for the contribution Felix gave to the national team," Brazilian Football Confederation (CBF) president Jose Maria Marin said in a statement. "He is an idol and will be greatly missed."
After retiring in 1976, he had brief stints as a manager and goalkeeping coach before leaving the game and working in business with his family. More recently, he worked coaching poor children.
He is the second of the great 1970 team to die and the first from natural causes. Full back Everaldo was killed in a car crash in 1974.
The CBF said one minute's silence would be observed at every Brazilian championship game this weekend.