The British cousins gained worldwide fame in 2011 when a video of them video of them performing Nicki Minaj's "Super Bass" went viral, and DeGeneres had them appear on The Ellen DeGeneres Show.
Last week the comedian celebrated her 60th birthday and shared a video that Sophia Grace, 14, and Rosie, 11 had recorded for her.
"We've had so many amazing memories, Ellen" Rosie says, before the girls list their best times on the show.
Sophia Grace says her favourite was when the TV host gifted the cousins Nikki Minaj style wigs.
Rosie's was getting slimed: "I loved it but it was freezing cold."
DeGeneres jokes that she feels older after seeing the girls all grown up.
"That's when you feel the aging, 'cause you see them age and then you compare it and so now, I feel old," she said.
"And Rosie wasn't even talking at the time. She never talks. She's talking now."