A second-half Barcelona goal-fest saw the Blauguarana side score all four goals in the second half. A goal from Antoine Griezmann and Frenkie de Jong was completed by a Messi brace.
Moreover, Barcelona took their revenge on Marcelino's Athletic Bilbao after being defeated in January's Super Cup Final.
The triumph now sees Barcelona having won their 31st Copa Del Rey title after three seasons without winning it - their last CDR trophy dating back to the 2018-19 campaign.
Messi's man of the match displayed once again why he's the man for the big occasion. A scintillating performance from the Argentine signified why he's regarded as the world's best player.
The number 10's first goal revitalised the term tiki-taka, it was a sensational passage of passing between De Jong and Messi, which saw the Argentine end the brilliant move by dropping the shoulder on Inigo Martinez to neatly finish past Bilbao's Unai Simon.
Messi's brace last night saw him break yet another record, becoming the leading goal scorer in Copa finals history with nine, eclipsing Telmo Zarra's total of eight.
Speaking to MARCA after the game, the Argentine admitted the trophy was a much-needed one for the squad. "It was a very tough competition, in many games we suffered. It is always nice to lift the title, very happy for this group that deserved joy."
Meanwhile, De Jong's excellent display showed his class in a cup final Barcelona could not simply afford to lose. From a central midfield role, the Dutchman provided two assists alongside his goal to cap off a total footballing night.
The 23-year-old has become a real thorn in a side that have not performed to their usual standards in seasons gone by.
Griezmann showed why Barcelona paid a big money fee for him as he bagged an all-important second Barcelona goal to ease the nerves after missing a huge chance earlier in the second half.
The Frenchman displayed his thoughts in the post-match conference saying, "We won the final. It was very important for us & the team. There have been difficult moments, but I’m very happy here. You can miss passes and goals, but I always give my best and I think that's what is most important. I want the best for the club”.
The start of Barcelona's new generation saw the likes of Ilaix Moriba, Ansu Fati, Ronald Araujo, Oscar Mingueza, Pedri and Sergino Dest all lift their first Copa Del Rey trophy as part of the future Catalan side.
An ageing side with footballing veterans in Messi, Sergio Busquets, and Gerard Pique lead by example to youngsters as the trio out mastered Bilbao with a vintage display to lift their seventh Copa Del Rey trophy together.
Ronald Koeman succeeded in winning his first silverware as manager of the club, but the talks of his managerial future at the club do not seem to vanish. The Barcelona legend addressed Barca TV after the game.
"In any big club, you know that the manager depends on the titles and results winning a title is also important for me. But above all for the players who have fought for everything from day one. If there's a team that deserves to win this Cup... It's us."
"My continuity? This decision is not in my hands. I have one more year of a contract and everyone knows what we're currently doing. At the end of the season, we'll see what has been won... Here you have to win things, and I'm responsible."
Barcelona's season could end on a high note, as they battle it out to win a nail-biting La Liga title race against Real Madrid and Atletico Madrid. Last night's cup win and this year's excellent form should give the Catalan side the much-needed momentum to win a title that could potentially be Messi's last.