The 'Call My Name' hitmaker spoke to the royal couple after she performed at the Diamond Jubilee concert at Buckingham Palace earlier this month and she was shocked that the William and Catherine - who used to be known as Kate Middleton prior to the pair's nuptials - were ''so normal''.
She said: ''I spent quite a bit of time chatting to Kate and William.
''She's just so normal. They're royals but they're not disconnected from us, they know what's going on in the world.
''They were just saying how happy they were with the performance and what a good night the queen had.
''I was a bit starstruck though, a bit like, 'Wow, these are our royals and I'm in Buckingham Palace having a drink'.
''Kate's doing really well. It must be tough being thrust into the limelight but she doesn't seem to flinch.
''She takes it in her stride. I love that she wears things twice. Welcome to The Real World.
''Kate's mother came over to me at one point and said, 'You've got Middleton dimples.' Pippa was gorgeous too.''
Cheryl admits she was ''overwhelmed'' by the occasion and says it was ''crazy'' performing alongside so many huge global stars.
She added to The Sun newspaper: ''The whole experience was overwhelming actually. You're in Buckingham Palace for a start, the whole of the Mall was packed with people waving flags - and then you had all the royals there.
''And I was singing with Gary Barlow. The craziest night of my life.
''You can't even imagine those moments. It's everything that you think of in a fairytale.''