The 32-year-old American singer and 40-year-old British actor got close at Sheeran's show Saturday in Los Angeles following their split in February after a year of dating.
"They definitely seemed like they're back together," a source told E! News. "They cuddled most of the night. She sat on his lap most of the night and shared kisses."
"They looked like they were having the time of their lives," the insider added. "People didn't really bug her. I don't really think people knew it was them because they had hats on and stuff."
Perry was all smiles in a red jacket and black skirt and baseball cap as she arrived at the concert on the back of Bloom's motorcycle, according to TMZ. Entertainment Tonight reported the pair had first-row floor seats at the show.
"Orlando put his arm around Katy's waist several times, and at one point, she sat on his lap," a source said.
"Orlando seemed to be having a great time and really seemed to enjoy the concert, even dancing at one point," the insider added. "Katy was more laid back and seemed to just be listening and taking it all in."
Perry and Bloom announced in a statement Feb. 28 that they were taking a break from their relationship. The singer later told fans she and Bloom are still "friends," and that no one was "a victim or a villain" in their breakup.