Philippe Coutinho scored his first Barcelona goal as the Spanish side beat Valencia to reach a record fifth successive Copa del Rey final.
Coutinho, making his fifth appearance since a £142m move from Liverpool, came on in the second half and acrobatically steered home from Luis Suarez’s cross.
That put Barca, cup winners in the past three years, 2-0 up on aggregate in the semi-final second leg in Valencia, before Ivan Rakitic added another.
Barca will face Sevilla in the final.
Valencia – who are third in La Liga, 18 points behind leaders Barca – had two key chances but were well beaten by a team that looks certain to win the league title.
At 0-0, striker Rodrigo headed against the crossbar while Jasper Cillessen produced a stunning instinctive save to deny full-back Jose Luis Gaya from point-blank range following Coutinho’s opener.
After Rakitic coolly rounded off a late counter attack, finishing from Suarez’s pass, Barca brought on 23-year-old Colombian defender Yerry Mina – a £10.4m January signing from Palmeiras – for his debut.
Sevilla, sixth in the Spanish table 25 points behind the leaders, reached their second Copa del Rey final in three seasons with a 3-1 aggregate win over La Liga rivals Leganes.
Barca have won the competition three times in a row since losing to Real Madrid in the 2014 final.