The Black Eyed Peas member spoke out about the royal Tuesday night in New York City at a fund-raiser to benefit Harry's charity foundation.
And the musician didn't hold back on his kind words at the fête, which was hosted at the Four Seasons Restaurant by the American Friends of The Royal Foundation.
"If you're American and you watch movies on the royal family historically, it seems [like] fantasy," the Grammy winner tells U.K.'s The Telegraph, "but to see the human in Harry, he's a normal guy."
The musician also gave props to Harry for his "beautiful heart and great upbringing," adding that it "makes you believe that your family is royalty as well."
"He doesn't have to do charity, he doesn't have to care, he could just be wild," Will.i.am explained.
"If he was a character in a movie, he would be like Iron Man," the beatmaster quipped. "He's a dude…he's a party guy, he's a technology guy, he comes from royalty, but he's a real person."
As for Harry, he's been keeping quite a busy schedule during his Stateside trip: Within the last week, he's met with Michelle Obama, tried his hand at American football and toured the Jersey Shore areas affected by Superstorm Sandy. Whew!