Pedro and David Villa scored two apiece and Xavi added the other as Barcelona won 5-1 to make it 10 wins in a row in all competitions and extend their unbeaten run to 22.
Espanyol's Pablo Osvaldo had briefly threatened something of a comeback making it 3-1 in the 63rd, when he became the first player to beat Victor Valdes in seven games, but the ever-hungry Barca snuffed out their revival with two more goals.
"My team never ceases to surprise me," Barca coach Pep Guardiola told reporters.
"Espanyol had only conceded two goals at home. It's a great night for us because we were aware we were playing a great team. It's no coincidence that we have struggled here a lot in recent times."
Earlier, Villarreal broke clear in third with a 3-1 victory over Real Mallorca, climbing on to 33 points, five ahead of Valencia and Espanyol.
Valencia moved above Espanyol on goal difference into fourth place after Aritz Aduriz pounced on an error to net a last-minute goal for a 2-1 win at Real Sociedad in the late game.
INIESTA OVATION
At Cornella-El Prat, Espanyol fans gave Barca's Andres Iniesta a standing ovation before kick-off and later when he was substituted, in recognition of the Spain midfielder's gesture after scoring the winning goal in the World Cup final.
Iniesta took off his shirt to reveal a vest with a dedication to former Espanyol captain Dani Jarque, who died of a heart failure last year aged 26.
Espanyol, who had held Barca to a 0-0 draw in the corresponding fixture last year and boasted a 100 percent home record at the start of the day, worked hard to take the game to their visitors.
Lionel Messi uncharacteristically shot over an empty net early on but made amends soon after when he played Pedro through on goal to score the opener in the 19th minute.
Xavi volleyed in from a tight angle as the hosts struggled to clear their lines in the 30th and Messi burst away from his markers to shoot on the hour. When Carlos Kameni could only parry his shot Pedro raced in to poach the third.
Osvaldo broke free to beat Valdes soon afterwards, lifting the home team but their high defensive line was punctured twice more.
Messi and then Xavi sent Villa scampering clear and the Spain striker gave Kameni no chance in the one-on-ones.
SUPERB NILMAR
Earlier, a superb finish from striker Nilmar topped off Villarreal's win at home to Mallorca.
The Brazilian raced through onto Borja Valero's pass in the 51st minute and, under pressure, lobbed visiting goalkeeper Dudu Aouate to score his 10th goal of the season.
Villarreal's neat possession football is reminiscent of Barca's and one such passage of play ended with Santi Cazorla volleying home in the 11th minute.
Jonathan de Guzman equalised against the run of play with a spectacular shot in t
