"Lambily 4lyfe," Perry posted on Instagram while standing admiringly before a giant poster for the singer's show Mariah #1 to Infinity. Perry looked glamorous while wearing white sunglasses, a shimmering blue dress and a pink stole tossed over her shoulder.
The 30-year-old singer then posted a photo of the two pop princesses backstage, wearing big smiles and low-cut dresses.
Perry also shared a video of the diva duo posing for the paparazzi, cameras flashing.
Courtesy Katy Perry
Perry and her friends caught Carey's Vegas residency a week before it is scheduled to end its run July 26.
In her show, Carey, 45, performs her 18 number one hits in chronological order, while – in typical Vegas style – sporting a number of costume changes and performing on elaborate props, including a neon yellow jet ski and hot pink Thunderbird convertible.