The X Factor boss commended the 'Someone Like You' singer's achievements in a traditionally shallow industry and praised her for remaining "down-to-earth" throughout.
"Adele is an incredible story," he told The Sun On Sunday. "You wouldn't have predicted this years ago when we were such an image-infatuated business.
"Here is somebody who has done everything her own way, gone back to basics and achieved this incredible success. She's one of the most down-to-earth people you'll meet - and she hasn't changed a bit."
It was claimed this week that Cowell is considering hiring Adele for the X Factor UK panel as a replacement for Kelly Rowland.
The songstress last week returned to the top of the UK album chart for a 21st week with her second album 21, which has sold in excess of four million copies in the country.
> Adele, Simon Cowell named most powerful people in music
Watch Adele perform 'Rolling In The Deep' at the Brit Awards below: