The 30-year-old pop star and 37-year-old singer-songwriter attended a Grateful Dead concert on the Fourth of July. Perry was spotted holding Mayer as they took in the band's second Fare Thee Well show.
Actors Woody Harrelson and Chloe Sevigny, singer Jenny Lewis and A Song of Ice and Fire author George R.R. Martin were also in the audience. Perry shared a photo of the colorful roses at the performance with the caption "grateful."
Perry and Mayer have been an on-again, off-again couple since 2012, and previously broke up due to their busy schedules. The pair were spotted kissing at a Met Gala after-party in early May, and were seen together at Disneyland weeks later.
Perry released her fourth studio album, Prism, in October 2013, and will kick off the sixth leg of her accompanying Prismatic world tour Sept. 22 in Lima, Peru. Mayer last debuted Paradise Valley in August 2013, which includes the singles "Paper Doll" and "Wildfire."