The Periquitos banged in one goal in the first half and three in the second in a dominating offensive display.
Héctor Moreno, Víctor Sánchez, Joan Verdú and Christian Stuani all scored for Espanyol.
Los Leones have a record of seven wins, 11 losses and five draws this season, which puts them in 15th place, only four points above the relegation zone.
Los Blanquiazules are in 13th place, just six points above the relegation zone with a record of seven wins, nine losses and seven draws after 23 games.
Espanyol's midfielders played were instrumental in the victory, buoying the team with goals and scoring opportunities.
Periquitos controlled the ball for a mere 30.5 per cent of the match of play while completing 157 passes and getting off nine shots.
Espanyol's attack revolved around Verdú, who completed 21 passes on the day, including eight to Sergio García.
The most effective of Espanyol's three substitutions was Víctor Álvarez, who, after replacing Simão in the 53rd minute, assisted on two scores.
The four attempts by Stuani were the most of any Espanyol player.
Kiko Casilla made five saves for Espanyol.Athletic Bilbao managed to dominate the possession game, and maintained control of the ball for 69.5% of the match.
Los Rojiblancos's players linked up for 491 passes and 35 crosses.Markel Susaeta had four shots for Athletic Bilbao, more than any of his team-mates.
Iker Muniain went off due to injury in the 24th minute and was replaced by Ibai Gómez.
The combination of Ander to Andoni Iraola was the most common during the match, as the two players connected 17 times.