A comical own goal and Sergio Busquets' opener put Gerardo Martino's men firmly in control of the Copa del Rey semifinal tie
Having watched on as Real Madrid completed a comprehensive 3-0 win over city rival Atletico earlier in the evening, Barca was similarly impressive in its semifinal first leg.
Sergio Busquets' opener a minute before the break set Barca on its way, before a comical own goal from Sociedad goalkeeper Enaut Zubikarai put the Catalans in the driving seat ahead of the return clash.
Despite early pressure from Antoine Griezmann in particular, Sociedad never looked like ending its 23-year winless run at Barcelona.
Coach Gerardo Martino was without Neymar once again due to his thigh injury, while new Real Sociedad signing Sergio Canales took a place on the bench.
The visitors' dynamic front two terrorized the Barcelona defense as early as the third minute when Carlos Vela latched on to Javier Mascherano’s failed clearance and teed up Griezmann on the edge of the area, but Jose Pinto punched his powerful half-volley away.
With 12 minutes on the clock, Cesc Fabregas wasted a glorious chance of his own as he hit Dani Alves' low cross straight at Zubikarai four yards from goal, and from the resulting corner Alexis Sanchez somehow missed the target after pouncing on a rebound.
Lionel Messi went even closer when he struck the crossbar with a curling free-kick 37 minutes in, before Vela had a penalty claim turned down after being hauled down by Mascherano.
The half ended with controversy as Busquets turned in Pedro’s pass to give Barca the lead and during the celebrations Sociedad’s Martinez received a straight red card for dissent.
Barcelona’s pressure was unrelenting and Sociedad was penned inside its own area for prolonged periods before Barca finally doubling the lead on the hour.
Fabregas played Sanchez through on a breakaway, and his shot came off the post. Under little pressure, Gorka Elustondo attempted to clear the ball across the face of goal, but instead blasted the ball in off the helpless Zubikarai.
Martino’s men continued to press as they sought to put the tie completely beyond doubt and although Alves missed a headed opportunity late on, the win was never in doubt.