Bloom picked Perry up and the two headed to the birthday bash venue - the Sunset Tower here.
"She was nervous about being spotted and entered quickly trying to cover up," an eyewitness stated.
Based on some photographs obtained by dailymail.co.uk, it appeared that the 31-year-old singer didn't want to be caught by paparazzi as she was seen covering her face with her hair while inside Bloom's car.
The eyewitness added that before entering the place, Bloom held the door open for Perry, who donned an oversized beige long coat atop a colourful dress.
"Orlando opened the door for her. They were holding hands in the car. They each rested their arms on the center console and they were definitely interlocked," the eyewitness said.
The party was also attended by the likes of Jason Bateman, Jennifer Aniston, Reese Witherspoon and Arnold Schwarzenegger.
Keshishian later posted on Instagram a photograph of herself along with some friends at a table, where Perry and Bloom also sat.
Perry and Bloom exited the restaurant separately, but then they got in Bloom's car together and left the place.
"He exited first and she followed a few minutes later and was seen talking to Bateman, his wife and a few others that were around," the eyewitness said.
"But when the valet brought their call, Bloom and Perry hopped in and went back to her place together."