Fresh from scoring another treble in England's 4-1 quarter-final win over the USA, Brewster was again clinical as the Young Lions punched their ticket to Saturday's final, where they will face either Mali or Spain.
Brewster opened the scoring in the ninth minute, firing home at the second attempt after forcing a save from Gabriel Brazao.
An equaliser from the Samba side threatened to derail England's hopes, with Wesley on target, but Brewster's second, another close-range finish, restored their lead before half-time.
With 15 minutes remaining, Brewster was at it again, turning home after superb build-up play from England, ensuring that they will contest Saturday's showpiece.
Born in 2000, Brewster joined Liverpool from Chelsea at the age of 15, and has enjoyed remarkable success since.
Brewster scored five times in 11 games for the Reds' U18 team, and has also netted six goals in 14 appearances for the U23s. In 16 caps for England's Under-17 team, he has scored 12 goals, after netting four in four for the U16s.
Capable of playing on both the left wing and through the middle, his rapid ascent through the ranks has not gone unnoticed at Anfield, and he was named on the bench for the club's 2-1 defeat to Crystal Palace last season.
England's young teams have enjoyed a spectacular 2017 thus far, reaching the final of the U17 European Championships, the semi-finals of the U21 Euros, and winning the U20 World Cup, the U19 Euros, and the U18-20 Toulon Tournament.
England's senior side head to Russia next summer to take part in the World Cup, having qualified for the tournament by winning Group F with an unbeaten record.