Julio Baptista put the Selecao in front after just four minutes, Argentine skipper Roberto Ayala fired into his own net before half-time, and substitute Daniel Alves concluded the massive victory with a third goal in the second half.
The victory ensured Brazil's supremacy over Argentina in the past couple of years, as they managed four victories out of four against their bitter South American rivals, including three successive wins by the three-goal margin.
Argentina entered the contest as definite favorites, as Brazil missed lethal duo Ronaldinho and Kaka, who were both rested during the competition, in addition to skipper Gilberto Silva, who had a slight injury and was relegated to the bench.
However, Brazil coach Dunga, who captained the Selecao in the 1994 World Cup triumph, managed to prove his brilliance in the first genuine test of his coaching career.
Baptista's early opener was vital as well as spectacular, as the Beast fired a perfect-placed shot into the top corner to pave way for Dunga's men, who dealt with the game in cool tactical mood afterwards.
After 34 minutes, Brazil lost midfielder Elano, who created Baptista's goal, after the Shakhtar midfielder was injured.
However, his replacement, Daniel Alves, proved to be a masterstroke by Dunga, as the Sevilla defender was to make his mark later in the game.
Five minutes from half-time, Daniel Alves whipped in a blistering cross into Argentina's area, and the hapless Ayala converted the ball into his own net.
Argentina scored 16 goals throughout the tournament, but they rarely threatened Doni in Brazil goal despite committing men forward.
In the 69th minute, Brazil punished Argentina in the counter, when Vagner Love released Daniel Alves with a smooth pass, and the Sevilla full-back fired in a low shot from a tight angle past Roberto Abbondanzieri.