Gerardo Martino's men picked up where they left off in their 2-1 Clasico win over Real Madrid on Saturday as Barca produced a fine performance to move four points clear at the top of La Liga ahead of Atletico Madrid, who face Granada on Thursday.
Alexis Sanchez gave Barca the lead after just nine minutes in what was his 100th appearance for the club, Celta goalkeeper Yoel parrying Cesc Fabregas' shot straight into the path of the Chile international, who slotted in from point-blank range.
Celta created chances throughout, but Barca put themselves in control three minutes into the second half as a long-range effort from Fabregas bounced off the bar before deflecting off the unfortunate Yoel and into the net.
Fabregas was at the centre of the the majority of Barcelona's attacks, and it he wrapped things up six minutes later when he powered home at the near post after being played through by Lionel Messi.
Barcelona's city neighbours Espanyol missed the chance to move into the top six as they were held to a goalless draw by Malaga.
Javier Aguirre's men were fortunate not to fall behind just before the interval, as Malaga duo Roque Santa Cruz and Eliseu both hit the woodwork.
However, despite those opportunities, the visitors will have been relieved to have taken a share of the spoils, with only a fine save from Willy Caballero preventing Espanyol striker Sergio Garcia from giving the hosts all three points four minutes from time.
The result leaves Bernd Schuster's side without a win in five matches.
