Barca were the better side throughout much of the encounter, holding 69% of the possession but were unable to take the game away from a stubborn Espanyol outfit that fought until the end.
The hosts' resolute defence was anchored by a proactive pressing game that made things difficult for Barcelona to break them down.
However, the Catalans have made a habit of finishing games strong - they have scored more goals in the final 15 minutes than any other team in LaLiga this season - and did so again against Espanyol.
The visitors opened the scoring in the 86th minute thanks to a delightful curling effort into the top corner by Dani Olmo.
Four minutes later, Fermin Lopez played in a beautiful ball for Robert Lewandowski to finish from close range to secure the result.
Espanyol's last success in the derby came back in 2009 but they can be very proud of their efforts on Saturday, as well as their overall performance this season which sees them occupying fifth place in the standings.
Elsewhere in LaLiga on Saturday, goals from Ruben Garcia (34') and Gorka Guruzeta (71') cancelled each other out as Osasuna and Athletic Club drew 1-1 at Estadio El Sadar.
Villarreal got the better of Elche at Estadio Martinez Valero, claiming a 3-1 victory despite having only 22% of the possession.
Alberto Moleiro opened the scoring in the seventh minute before George Mikautadze doubled their advantage six minutes later.
Martim Neto pulled one back for the hosts around the half-hour mark but Elche's search for an equaliser was eventually trumped in the 83rd minute when an Alfonso Pedraza strike made it 3-1.
Celta thrashed Valencia 4-1 at Estadio Abanca Balaidos with most of the action coming in the second half of play.
Borja Iglesias opened the scoring for the hosts from the penalty spot in the 30th minute in a tense first half with the action picking up after the break.
Iglesias added his second of the game in the 59th minute with Pepelu pulling one back in the 70th minute.
Jones El-Abdellaoui restored their two-goal advantage in the 83rd minute and Hugo Alvarez made the result secure with a strike deep into stoppage time at the end of the match.