Leading 1-0 from the first leg in Monterrey, the visitors blew away Cruz Azul in a stunning opening 25 minutes in which it opened up a 3-1 lead.
Maximiliano Meza and Orbelin Pineda traded goals within the opening 10 minutes, before Duvan Vergara and Rogelio Funes Mori netted to make it 3-1.
Mexican international Funes Mori added another in the 52nd minute to complete the win for Monterrey, which was the CONCACAF Champions League winner in 2019.
Carlos Rodriguez found Meza unmarked inside the box, dispatching a low finish off the post for a seventh-minute lead and 2-0 advantage on aggregate.
Guillermo Fernandez teed up Orbelin Pineda for a low drive from a set-piece to equalise in the 10th minute.
Vergara curled in a spectacular 17th-minute goal after Meza's initial cross was over-hit, before Monterrey goalkeeper Esteban Andrada made a fine save to deny Fernandez.
Funes Mori made it 3-1 in the 24th minute, after a lengthy video assistant referee (VAR) review for offside, with a sweeping first-time left-foot finish.
Andrare denied substitute Bryan Angulo, before Funes Mori worked a one-two with Meza to settle the contest early in the second half.
Monterrey will face America in an all-Mexican final on 29 October (AEST) in Guadalupe.