Perry, 29, called her 'Queen' Adele after she attended the second night of her four-show residency in the capital, reported Digital Spy.
"... And on the 2nd London show the Queen graced me with her presence," Perry said.
Adele is the latest star to enjoy Perry's Prismatic World Tour, after Sam Smith, Nick Grimshaw and Jessie Ware.
The 'Roar' hitmaker launched her new world tour in Belfast earlier this month, before visiting cities like Liverpool, Manchester and Nottingham.