The former Bake Off judge and Never Gonna Give You Up singer surprised fans with their unlikely pairing at Dorset's Lulworth Estate on Friday night.
It is not clear why Berry ended up onstage but Astley earlier tweeted he had "bumped into" the TV chef onsite.
Looking forward to playing @CampBestival tonight... Look who I just bumped into! The wonderful Mary Berry! For those of you at #CampBestival, I'll see you on the #CastleStage tonight at 10pm! - Rick x pic.twitter.com/hfu1toEVyM— Rick Astley (@rickastley) July 27, 2018
Event organiser Rob Da Bank described it as one of the festival's "odder moments".
Mary Berry playing drums with Rick Astley at Camp Bestival?! You’ll find out why soon... pic.twitter.com/CEcgH51v1v— Camp Bestival (@CampBestival) July 27, 2018
We aren't sure why this video exists all we know that it is brilliant!
My mum has just recorded a video of Mary Berry drumming for Rick Astley live.— Weeby 🏴 (@WeebyMcWeebface) July 27, 2018
What a timeline we live in. pic.twitter.com/44VjgIjbHb