Two goals from Bruno Henrique -- who also bagged a double in last week's first leg win in Rio -- fired Flamengo into the final, the Brazilians completing a 4-0 aggregate victory.
It means that the November 27 final of South American club football's showpiece tournament will be an all-Brazillian affair for a second straight season after Palmeiras faced Santos in the 2020 tournament.
Flamengo will be chasing a repeat of their triumph in the 2019 final when the Brazilians defeated Argentina's River Plate in Lima.
On the evidence of the semi-finals, Flamengo will fancy their chances of lifting the Libertadores for the third time in the club's history.
The Rio club produced another clinical performance at Barcelona SC's Estadio Monumental in northern Ecuador.
Flamengo effectively killed off the tie midway through the first half when Henrique scored his first of the night.
A perfectly weighted pass from Everton Ribeiro split Barcelona's defence and Henrique, timing his run to perfection, latched onto the through ball, rounded Javier Burrai and coolly stroked his finish into the empty net.
That left Barcelona needing to score four goals to have a chance of progressing, which always looked unlikely against a technically superior Flamengo side.
Mario Pineida squandered a golden chance to pull a goal back for Barcelona on 20 minutes when he shot straight at Flamengo goalkeeper Diego Alves.
At the other end, Flamengo almost doubled their lead when Andreas Pereira, on loan from English giants Manchester United, lashed a long range shot against the post.
Another Barcelona chance went begging on 24 minutes when Luis Leon's free-kick was saved by Alves, only for Leandro Martinez to lash the rebound over the bar.
Flamengo then sealed victory on 50 minutes, when a slick counter-attack saw Ribeiro break forward and slide a pass to Henrique who once again delivered the finish for 2-0.
Standout matches today