Esteban Granero struck to give Real the lead just before the break, Guti made it 2-0 in the 77th minute and Ronaldo wrapped up the victory in added time.
It was an emotional evening for the Espanyol players and fans as it was their first home league match since captain Dani Jarque collapsed and died last month and their first competitive game in their new Cornella-El Prat stadium.
Barcelona had earlier got their second win from two when Ibrahimovic made up for a glaring miss in the first half by scoring one and creating the clinching second for Lionel Messi.
Barcelona, who have yet to concede, are top with six points, ahead of Real on goal difference.
Real coach Manuel Pellegrini left record 94 million euro signing Ronaldo and captain Raul out of his starting line-up and Espanyol had the pick of the chances in the early stages.
Granero's goal came after he exchanged passes with Brazilian playmaker Kaka and finished past goalkeeper Carlos Kameni.
Kaka, signed from AC Milan for 67 million euros in the close season, then surged to the byline and cut the ball back for Guti to double the lead with just over 10 minutes left.
Ronaldo replaced the ineffective Karim Benzema and was on hand to slot into an empty net for Real's third.
Pellegrini told a news conference the poor state of the new pitch had made it difficult for the players and he had been impressed with Ronaldo's performances for his new club.
"Cristiano is adapting to the league and the team," he said. "To me, he seems very content."
SUPERB VOLLEY
At Getafe's Coliseum, Barca coach Pep Guardiola left Messi, Thierry Henry, Daniel Alves and fit-again Andres Iniesta on the bench and the European champions came under early pressure.
Juan Albin almost grabbed an 11th minute lead with a superb volley from just outside the penalty area that ricocheted down off the crossbar with Victor Valdes rooted to the spot.
Valdes could only stand and watch again when an overhead kick from Roberto Soldado, who scored a hat-trick against Racing in Getafe's opening match, bounced back off a post.
Guardiola brought on Messi and Iniesta just before the hour and they took the lead almost immediately when Ibrahimovic stuck out a leg to steer the ball in off a post from Eric Abidal's deflected cross.
The Swede then underlined his class when he controlled an Alves centre on his chest and chipped a perfect first-time cross for Messi to power in a rare headed goal.
"Getafe fought for the ball today more than any team we have played since I became coach," Guardiola told a news conference. "Winning here is not easy and the victory is worth a lot."
Brazil striker Luis Fabiano netted twice and forward Diego Perotti scored a stunning drive in Sevilla's 4-1 win over visiting Real Zaragoza and Atletico Madrid were held 1-1 at home by 10-man Racing Santander.
