Cristiano Ronaldo netted two early penalties to give Real Madrid a 2-0 win at King's Cup holders Atletico Madrid which sent them into the final 5-0 on aggregate.
Real, who have not conceded a goal in this season's competition, are likely to meet Barcelona in April's showpiece as the record winners lead 2-0 against Real Sociedad ahead of Wednesday's semi-final, second leg in San Sebastian.
We did our job and got through to the final and now our focus turns to La Liga and the Champions League.
"I think the first leg was the key as a 3-0 lead meant we were very well set for the return," Real goalkeeper and captain Iker Casillas said in an interview with Spanish media.
"And then scoring the two early penalties meant the tension was taken out of the tie," added the Spain international.
"We did our job and got through to the final and now our focus turns to La Liga and the Champions League."
Real's 3-0 win in last week's first leg at the Bernabeu was sweet revenge both for their bitter 2-1 defeat to Atletico in last year's final and a 1-0 reverse in La Liga at the end of September.
Atletico, missing suspended top scorer Diego Costa, faced a huge task to turn the tie around in the return across town at the Calderon and they got off to the worst possible start when teenage defender Javier Manquillo tripped Ronaldo in the penalty area in the sixth minute.
The Portugal forward smashed the spot-kick past Daniel Aranzubia and things went from bad to worse for the home side when Emiliano Insua felled Gareth Bale and the referee awarded another penalty.
Atletico forward Raul Garcia had crashed a shot against the post minutes earlier but Ronaldo buried the penalty into the corner to make it 2-0 with only 16 minutes gone.
Ronaldo, who is serving a three-match La Liga ban after being sent off for violent conduct, had an eventful end to the first half when he was booked for an aerial challenge on Manquillo and was hit on the head by a cigarette lighter as he left the pitch at the break.
The FIFA Ballon d'Or winner did not appear to have sustained any injury and played most of the second half before making way for Jese.
Manquillo landed awkwardly and suffered neck damage before being transferred to hospital for checks as Atletico slipped to their third straight defeat, including Saturday's 2-0 loss at Almeria in La Liga.
Real, level on 57 points with Barca and Atletico at the top of La Liga, are in excellent form as the season enters a critical period.
Carlo Ancelotti's side can now concentrate on preparing for their next two La Liga games against Getafe and Elche before they travel to Germany to face Schalke 04 in a Champions League last-16, first-leg match on 26th February.