The 32-year-old, who worked as a stripper before finding fame in Hollywood, says he first thought the magazine was playing a prank on him.
Tatum says his wife Jenna Dewan now makes fun of him and his title.
"My first thought was, 'Y'all are messing with me. I told Jenna after we'd been in the bathtub washing our dogs because they'd gotten skunked. She was like, 'What?' Yeah, she calls me the Sexiest Man Alive now," he said.
Although Jenna, 31, is happy to be married to the Sexiest Man Alive but says there is more to her husband than just his handsome looks and toned body.
"People know him to be fun and sexy, but they don't know how emotionally deep and spiritually open he is. He is such an open-hearted person; what you see is what you get," she said.
Channing also revealed he and Jenna, 31, are planning to start a family and he is keen to have lots of kids.
"I'm ready; I think she's ready. The first number that pops into my head is three, but I just want one to be healthy and then we'll see where we go after that," he said.
