The 34-year-old lead singer of Maroon 5 and judge on NBC's "The Voice" is replacing current title holder Channing Tatum.
"As a musician, you have fantasies that you want to win Grammys, but I didn't really think that this was on the table," Levine told the magazine. "I was just amazed and stunned and it almost seemed like they were kidding, but they weren't, so that's cool."
Levine will officially accept his new "sexiest man alive" title Wednesday night on late-night talk show "Jimmy Kimmel Live!" at 11:35 p.m. PT on ABC7.
Levine got engaged to Victoria's Secret model Behati Prinsloo earlier this year.
He is one of the only musicians to ever be given the honor. He joins the ranks of Bradley Cooper, Ryan Reynolds, Brad Pitt and George Clooney, who all have received the honor. In 1984, Mel Gibson became the first actor to be given the title by the magazine.
The annual "sexiest man alive" issue of People magazine hits newsstands on Wednesday in Los Angeles and New York, and nationwide on Friday.