The 41-year-old country music star was given the title by the publication earlier this week, and fellow musician Kelly - who is on the judging panel alongside Blake on 'The Voice' - thinks his sex appeal comes from his sense of humour, rather than his good looks.
She said: ''He's sexy. Let him be sexy! Sexy is different to everyone. And he's a jokester. I think I like that about him. He didn't vote himself that - obviously People magazine did. I think it's funny that he takes it with a grain of salt and he also takes the criticism the same way.''
The 'Piece By Piece' hitmaker - who has River, three, and Remington, 19 months, with her husband Brandon Blackstock - is close friends with Blake and his girlfriend Gwen Stefani, and gushed about their ''chill'' double dates.
She added: ''Recently we did get to hang at Gwen's house, which is insanely gorgeous. It was really cool. Brandon, Blake and I, we're all southern. Gwen's a southern Cali girl, yes, but I just mean ... we're all different. I think the common denominator is that we're all very chill, we love what we do, we're just kinda all normal kids. It sounds really funny.''
But Kelly wasn't so calm when she first met Gwen, as she couldn't believe she was hanging out with the former No Doubt musician, who she grew up listening to.
Speaking to Entertainment Tonight, she said: ''And God, I grew up listening to Gwen, from No Doubt days. So, it's just really cool. She's really sweet and down-to-earth. And [Blake's] sweet and down-to-earth, my husband's like that. We're all just kinda very chill.''