Messi curled in the opener in the 30th minute from outside the area following clever link up play with Neymar after Alaves, who were playing in their first domestic final, had struck the inside of the post.
The Basque side drew level three minutes later when Theo Hernandez fizzed a spectacular free kick into the top corner although Neymar restored Barca's lead a minute before halftime, bundling in Andre Gomes's pass from close range after starting the move with a dazzling run down the left.
Paco Alcacer further stretched the Catalans' lead two minutes later killing off Alaves' hopes of a first trophy in their 96-year history and delivering Barca's 29th King's Cup, the ninth trophy of Luis Enrique's three-year tenure.
"Nine trophies in a club like Barca, who have had a glorious decade, means that the players have been at their very best and I was able to enjoy it. These trophies were down to the players and their ambition," Luis Enrique told reporters.
"It's great to finish the season with a trophy and not go home empty handed. We've won another trophy, but the team gave their best in every game.
"I feel satisfied about a job well done and I can't wait to rest, to be with my family and enjoy some well deserved holiday."
Luis Enrique said he had no plans for the immediate future and is expected to take a sabbatical year before plotting his next move.
Former Athletic Bilbao coach Ernesto Valverde is set to be named as his successor on Monday, according to reports in the Spanish media.
RAMPAGING RUN
Barca were searching for one piece of silverware to end a disappointing campaign after surrendering the Liga title to Real Madrid and exiting the Champions League in the quarter-finals to Juventus and were without prolific striker Luis Suarez and defender Sergi Roberto through suspension.
They suffered an early setback when Javier Mascherano was carried off on a stretcher following a head-on collision with Alaves midfielder Marcos Llorente, who had to sport a bandage on his head for the rest of the game.
Alaves brought an extra 2,000 fans to the Vicente Calderon than their illustrious opponents and were dreaming of a repeat of their shock league win at the Nou Camp earlier in the season, although this time Barca were fielding a far stronger starting line-up.
Alaves nearly took a surprise lead when Gerard Pique gave the ball away to Ibai Gomez, who fired under Jasper Cillessen and off the inside of the near post, watching the ball trickle just beyond the far post.
Messi's brilliant strike, his fifth goal in seven King's Cup finals, did not crush Alaves and they quickly drew level with the thunderbolt free kick from Theo, a loan signing from Atletico Madrid who is expected to join champions Real Madrid in the summer.
But Messi and Neymar had not finished yet. The Argentine fed substitute Gomes who teed up Nemyar and barely two minutes later Messi went on another rampaging run through the middle to play in Alcacer and ensure there was no way back for Alaves.
(Reporting by Richard Martin; Editing by Rex Gowar and Pritha Sarkar)
source: news.abs-cbn.com
