Neymar scored his first league goal in Spanish football as Barca turned in arguably their best performance so far under new boss Gerardo Martino.
The Brazilian bundled home Alexis Sanchez's cross after just five minutes and then expertly teed up Lionel Messi to plant a diving header past Claudio Bravo three minutes later.
Sergio Busquets added a third before half-time with a sweet strike from 20 yards to register his first goal of the season and Marc Bartra rounded off the scoring for the hosts after Alberto de la Bella had pulled a goal back for Sociedad. "I am very happy to score my first goal in the league but the most important thing is the victory," Neymar told Canal Plus television. "We are playing very well. Every game we seem to get better and I am enjoying it more and more."
Amazingly, the visitors had made the brighter start with Haris Seferovic striking the bar from 20 yards inside two minutes.
However, the game was virtually lost for them just six minutes later.
Firstly, a horrible defensive mix-up between Liassine Cadamuro and Bravo allowed Neymar to bundle home his first and possibly the easiest goal he will ever score for Barca at the Camp Nou.
And three minutes later the Brazilian delivered a perfect left-footed cross from which Messi headed home at the far post.
It didn't take the hosts long to register their third of the evening as Messi's backheel was well saved by Bravo, the Argentine's follow-up effort somehow hit the bar and post on its way out and Busquets finally fired home the rebound from outside the area.
Barca were then dealt an injury blow as Javier Mascherano came off with a hamstring problem to be replaced by Bartra 10 minutes before the break.
However, the hosts were still in full flow and nearly produced a goal of the season contender as Messi, Xavi, Andres Iniesta and Neymar all combined inside the area before Messi unbelievably failed to connect properly on his left foot to turn Neymar's cut-back home.
Messi wasn't having his best night in front of goal as he blasted another glaring opportunity over the bar after accelerating past three defenders at the beginning of the second period.
Real were then given a glimmer of hope when Agirretxe did well to hold off Gerard Pique and square for De la Bella to tap home 26 minutes from time.
However, Barca's three-goal advantage was restored 12 minutes later when Messi wriggled his way towards the by-line and his low cross was guided home by Bartra.
Atletico meanwhile made much harder work of registering their sixth straight victory with a 2-1 win over struggling Osasuna.
Diego Costa had put the hosts in a commanding position with two goals inside the opening 25 minutes, but Oriol Riera halved the deficit for the visitors just before half-time.
Diego Simeone's men then passed up a host of chances to make the game safe in the second period, but held on for the three points to ensure they will head into Saturday's derby against Real Madrid at least two points ahead of Los Blancos.
Elsewhere, Malaga continued their recent revival with a 2-0 win over Almeria thanks to second-half goals from Fernando Tissone and Francisco Portillo.
And Valladolid held on to claim a point in a 1-1 draw away to Levante despite playing the entire second-half with just 10 men.