The Jaguares thrashed the Brumbies 39-7 to move into their first Super Rugby final on Friday.
A fast start in Buenos Aires helped the Jaguares secure their spot in the decider, scoring 20 points in the opening 20 minutes at Estadio Jose Amalfitani.
Matias Orlando crossed for two second-half tries and Joaquin Diaz Bonilla finished with 14 points off the boot in a convincing win.
The Jaguares will face either the Crusaders or Hurricanes in the final.
There was no looking back for the hosts after a dream start, Tomas Cubelli capitalising on a Brumbies error to score before Tomas Lavanini went over from close range.
The Brumbies responded on the stroke of half-time through Folau Fainga'a, but that was as close as they got.
Orlando scored on the counter-attack after a Matias Moroni pass and then went over again in the 63rd minute to wrap up the Jaguares' win, with Emiliano Boffelli adding to the scoreline later on.