Katy was invited to sing at the dinner celebration on Thursday night (31 July) to mark the 46th anniversary of the Special Olympics.
The 29-year-old popstar, who has been a long-time supporter of Obama, looked immaculate in the sequinned floor-length gown.
It turns out Obama is a pretty big fan of Katy too. Introducing her to the stage, he said: "We have just one of my favourite people performing tonight - Katy Perry. We are so grateful to her."
Obama continued: "I love Katy Perry. She is just a wonderful person. I've met her mum and now I know why she is such a wonderful person, but I just want everybody to know she is on tour right now and so for her to take time out to do this is really special, and so we really want to say thank you to her for doing this."
Who knew Obama was such a fan?!
Also in attendance at the dinner was music legend Stevie Wonder and former tennis ace Andy Roddick with his model wife Brooklyn Decker.
Taking to Twitter after the event, Katy said: "What an incredibly beautiful evening being invited to sing at the White House for Potus, Flotus & many special Olympic attendees tonight to celebrate these incredibly inspiring men & women. I see them beyond their obstacles. I hope you can join me."
To top off Katy's day, she also released the music video for her new single, 'This Is How We Do'.
She added: "Between singing at the White House & releasing one of my favourite videos, today was a good one. #ThisIsHowWeDo."
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Watch Katy's video for 'This Is How We Do' below: