Former Real player Samuel Eto'o put Barca in front just before the half-hour when he made the most of a defensive mix-up to notch his 10th goal of the season.
Dutch defender Giovanni van Bronckhorst doubled the Barca lead just before the break when he drilled home at the far post and the outstanding Ronaldinho wrapped up a brilliant win from the penalty spot after Eto'o had been brought down in the area.
The win allowed Frank Rijkaard's side to open a seven-point lead over Real at the top of the table after 12 games of the season.
Earlier last season's champions Valencia finally broke their 10-match winless run after goals from Italian striker Bernardo Corradi and midfielder Xisco gave them a 2-0 win at Malaga.
Deportivo Coruna notched their second win in a row with a 2-0 victory at Villarreal to inflict a first home defeat of the season on Manuel Pellegrini's side who were reduced to 10 men in the last 20 minutes after the sending off of defender Rodolfo Arruabarrena.
There was a breathless start to the game at the Nou Camp with Barcelona pinging some neat passes around the midfield and putting the visitors under pressure.
Real tried to stem the tide of Barca attacks by crowding out the midfield and feeding the ball to Luis Figo and Roberto Carlos on the flanks but they were always on the back foot as the Catalans dictated the pace of the game.
Barca went within a whisker of taking the lead midway through the half after Ronaldinho Deco and fullback van Brockhorst sliced open the Real defence with a dizzying passing move and Eto'o's sharp backheel was stopped on the line by keeper Iker Casillas.
Real kept defending on the limit but the incessant pressure eventually took its toll when a misunderstanding between Casillas and Roberto Carlos let the live-wire Eto'o put the home side ahead.
Ronaldinho swept a curling pass towards the edge of the area Roberto Carlos hesitated as he waited for Casillas to pick up but Eto'o darted between the two and sent the 98000 crowd wild running the ball into the open net.
Real never looked comfortable and were restricted to a couple of long range chances full back Michel Salgado firing into the side netting and Zinedine Zidane lifting the ball over the bar from two metres outside the area.
Barca upped the pace still further just before halftime and made it 2-0 after Ronaldinho and Deco dissected the Real area with two one-touch passes and van Bronckhorst drilled home past a bemused Casillas at the near post.
Real coach Mariano Garcia Remon tried to spice up his attack by replacing David Beckham with fellow England international Michael Owen. The former Liverpool player almost pulled a goal back when he sent a glancing header past the post after a Figo cross.
But it was Barca who continued to dominate the ever-smiling Ronaldinho showcasing his repertoire of ball skills and Eto'o continuing to torment the Real defence.
Eto'o pounced on a poor pass from Zidane in the middle of the pitch streaked his way down field into the area and was eventually brought down by a desperate Guti.
Ronaldinho smashed home the resulting penalty to complete a comprehensive win for the home side 15 minutes from time.
LARSSON COULD BE OUT FOR SEASON
Barcelona striker Henrik Larsson could miss the remainder of the season after tearing the anterior cruciate ligament in his left knee the Spanish club said on Monday.
The extent of the injury was revealed by keyhole surgery performed by club doctors on the Swedish striker's knee on Monday to repair cartilage damage sustained during Saturday's Primera Liga victory over Real Madrid.
Barcelona's official website said Larsson had asked for any surgery on the torn ligament to be postponed making it difficult to estimate how long the 33-year-old player would be out of action.
'By the player's express wishes definite surgery on the anterior cruciate ligament has been postponed' the club quoted a medical statement as saying.
Barcelona who are at home to Larsson's former club Celtic in the Champions League on Wednesday said the injury was at least as serious as those suffered by Larsson's team mates Thiago Motta Gabri and Edmilson.
Brazil midfielder Edmilson suffered damage to the same ligament in his right knee early last month and was ruled out for at least six months.