Saprissa earned a 1-1 draw against Alajuelense at the Estadio Alejandro Morera Soto on Monday, which was enough to see Jeaustin Campos' men triumph 2-1 on aggregate.
The San Juan de Tibas-based outfit - who scraped into the semi-finals after claiming the fourth and final play-off spot - took a slender one-goal lead into the second leg thanks to their last-gasp 1-0 win in the semi-final first leg.
Saprissa - the most successful club in the Costa Rican Primera Division after taking out the 2014 Torneo de Verano title - extended their buffer over Alajuelense in the 42nd minute.
Deyver Vega was on hand to net the opener three minutes before half-time, putting the visitors two goals clear via a priceless away goal.
Jose Ortiz did manage to pull a goal back for Alajuelense on the hour mark but it proved nothing more than a consolation for the home side, who topped the standings during the regular season.
Herediano played out a goalless draw at home to Cartagines on Sunday to set-up a showdown with Saprissa.
Neither Herediano nor Cartagines could find the back of the net at the Estadio Eladio Rosabal Cordero as Jafet Soto's side won 3-2 on aggregate.
The final will be played over two legs, with the opener taking place at the Estadio Ricardo Saprissa Ayma on December 14.