Brazil substitute Lucas Paqueta scored in the 46th minute and it proved to be the winning goal on Friday, despite Gabriel Jesus' remarkable red card in Rio de Janeiro.
Jesus was sent off for a high boot to the face of Chile's Eugenio Mena two minutes after Paqueta's strike, but Tite's Brazil withstood an onslaught from La Roja to set up a final-four showdown with 2019 runners-up Peru.
Brazil had entered the clash having won their previous for Copa clashes with Chile – scoring 11 goals and conceding just once across the streak, while the team's 10-game winning streak was snapped following a draw against Ecuador in the final group-stage match.
Chile also welcomed back star forward Alexis Sanchez for his first appearance at this year's CONMEBOL showpiece following a calf injury.
Roberto Firmino came within a whisker of opening the scoring in the 22nd minute, but the outstretched Brazil forward was unable to get on the end of Neymar's perfect delivery at the back post.
Eduardo Vargas – alone up front – twisted and turned to fire a shot off from an angle, but Brazil goalkeeper Ederson got down low to make a fine save minutes later.
Chile goalkeeper Claudio Bravo was forced into action approaching half-time, tipping Jesus' powerful shot over the crossbar after Neymar's pass bobbled into the forward's path.
Paqueta came off the bench and broke the deadlock within a minute of the second half starting – firing a ball past Bravo following a neat flick from Neymar.
Brazil celebrated wildly but their mood quickly changed when Jesus saw red for a shocking karate kick to the face of Mena just moments later.
Chile put the ball in the back of the net via Vargas in the 62nd minute, however, it was immediately ruled out for offside.
A great driving run form Neymar almost resulted in a second goal for Brazil after 67 minutes, but Bravo made himself big to thwart the Paris Saint-Germain man.
Minutes later, a looping header from cult figure Ben Brereton then dropped onto the crossbar as the substitute nearly restored parity for Chile, who continued to push players forward.