Valencia: Real Madrid defeated arch-rivals Barcelona 1-0 after in a dramatic finale to win the Spanish Cup for the first time since 1993. (Agencies)
A header from Cristiano Ronaldo sealed the championship, delivering coach Jose Mourinho's first trophy since joining the club last May.
As the final whistle blew in Valencia, fans in Madrid honked car horns and descended into the streets wrapped in the Real Madrid and Spanish flags or waving them in joy.
In central Cibeles Square, traditional home of Real Madrid victory celebrations, thumping music blared into the early hours, lights beamed the team logo across the city hall facade, and fans chanted: "Champions, Champions."
Last weekend Real ended a run of five straight defeats against Barca with a 1-1 draw in the league but at the Mestalla Stadium they went one better with their first trophy since 2008.
There still remain two more mouth-watering matches between the rivals in the Champions League on April 27 and May 3.
"This victory was for the fans as things haven't gone well at the club over the last few years. Mourinho is phenomenal," said Real goalkeeper Iker Casillas.
Mourinho admitted that there was little to choose between the teams.
"I thought it was a great game where players worked hard, were concentrated and did what they had to do," he said.
"Barca are a side which is used to winning and when they didn't score they became frustrated. I was told recently that I was a great coach for titles but not for football – I am happy to remain that way. I have won four cups now in four countries."
But Mourinho does not believe this victory will have any bearing on the upcoming Champions League clashes.
"We have now won one each and drawn a game this season, so who knows what will happen in the next. I don't think what happened in one game influences another."
Barcelona coach Pep Guardiola hopes his players will bounce back quickly.
"We didn't play well and control the game like we wanted to do and lost the ball a lot," he said.
"We need to lift ourselves for the next games. Madrid played very well in the first half but they performed as I thought they would. It was a similar system as at the Bernabeu but perhaps with some different players."
As expected Carles Puyol was not fit to start for Barcelona after picking up a hamstring strain in his return at the weekend which followed three months on the sidelines with a knee injury.
Instead Javier Mascherano was preferred to link up alongside Gerard Pique at the back.
The surprise in the Real formation was that Mourinho chose to play without a typical centre forward and instead lined up Mesut Ozil with Ronaldo and Angel Di Maria in a three-pronged attack.
Xavi had a shot from distance but Barca were unable to play their usual quick-passing game and both sides looked close to losing their composure in the frenetic atmosphere.
It was Real who were posing the greater threat.
Ronaldo took the ball too wide and his shot across the goal was cleared off the line by Mascherano.
Ozil fired wide from the edge of the area and then Ronaldo again from a tight angle saw his shot saved by keeper Jose Pinto.
The combative Pepe deployed in midfield was doing an excellent job to break-up Barca's play although he had to be cautious after picking up a yellow card.
In an all-action display he went within inches of scoring with a fine diving header which came back off the post.
However, it appeared as though Real had run out of steam after the break as Andres Iniesta and Xavi Hernandez took control of the midfield.
Pedro Rodriguez and Messi both shot wide while Real brought on Emmanuel Adebayor as they tried to change the direction of the game.
Casillas kept Real in the match with several vital interceptions against Messi and Pedro before an excellent save to deny Iniesta.
Di Maria just had time to see a shot tipped over by Pinto before the referee signaled 30 minutes of extra-time.
Ronaldo seemed to find another gear as he first fired narrowly wide and then went on to score the winner.
Di Maria and Marcelo combined well down the left wing before the Argentine crossed for Ronaldo to head home at the back post in the 103rd minute.
Valencia: Real Madrid defeated arch-rivals Barcelona 1-0 after in a dramatic finale to win the Spanish Cup for the first time since 1993.