The 'AKA... What A Life!' singer said that Cowell's honesty would be an improvement on many execs and industry workers that he had dealt with during his career.
"Simon's alright you know. I tell people and they're horrified, but it's true," the ex-Oasis star told ShortList.
"If the music business was full of people like him, it would be a better place because he's real - he's not a bulls**tter.
Gallagher's debut solo album Noel Gallagher's High Flying Birds is heading to number one on the album chart this weekend, ahead of X Factor winner Matt Cardle.
> Noel Gallagher turned down X Factor: 'My daughter has never forgiven me'
> Noel Gallagher: Simon Cowell wanted me as X Factor alpha male
Watch the music video for Noel Gallagher's 'AKA... What A Life' below: