The 53-year-old TV star said that the 'Heroes' singer has so far refused to accept a judging role, but the offer to join the show's line-up is still open.
Speaking to the Daily Mail, Cowell described Bowie as a "legend" and hinted that he'd approached the singer-songwriter with the suggestion that he sign up as a mentor multiple times.
"It's no secret I've asked him, and he hasn't said yes yet, but I'll keep extending the invitation," he said.
"Why Bowie? He's a legend. He's a great songwriter, he has massive influence on music today and he's 100% credible.
"I'm a fan - not just of his music but of him, the man. He's cool. Most of us aren't. Bowie is."
The music mogul - who gave up his spot on the British judging panel to