Miguel Layun scored a stunning free-kick as Monterrey twice came from behind to beat hosts Sporting KC and claim a crushing 10-2 aggregate victory.
MLS outfit Sporting KC faced an uphill battle following their humiliating 5-0 defeat to the three-time champions in the first leg last week.
Gerso Fernandes put Sporting KC ahead on the night thanks to his sixth-minute opener at Children's Mercy Park, though their slim hopes of reaching the final were dashed by Rogelio Funes Mori 14 minutes later.
Fernandes struck again in the 29th minute but Rodolfo Pizarro – like team-mate Funes Mori – responded to restore parity 10 minutes prior to halftime in Kansas City.
Aviles Hurtado and Funes Mori sealed the semifinal rout during the closing stages as Monterrey progressed to the Champions League decider for the first time since 2013.
The two-legged final will get underway later this month, with Mexican rivals Tigres hosting the first match.