The "Truth Hurts" hitmaker missed the birthday greeting when her idol first posted it on Monday, and jumped on the photo-sharing site to capture her reaction when she eventually saw it.
"Beyonce wished me a happy birthday. Beyonce wished me a happy birthday on her website," Lizzo said in a selfie video.
Holding back tears, she added, "She knows it's my birthday. Thank you, Beyonce. Oh, my God, thank you, Beyonce. She knows. She knows I exist... I don't know what to do with myself... Gonna sit with that one for a while."
She then thanked fans for their birthday wishes, adding, "It's so sweet... and I'm very hungover, so I'm gonna just lay here."