The cover of the magazine features the Grey's Anatomy star shirtless, holding the baby, with Gayheart standing behind him and his daughter.
"She's beautiful," Dane, 37, tells the magazine. "When she came out, she was really alert and her eyes were open. The doctor gave her to her mom, and I was so ... you know, I was obviously very emotional."
The couple's first child was born March 3 in Los Angeles — a day Gayheart, 38, described as "probably the greatest moment in my life thus far."
Dane said fatherhood has been a life-changing experience. "It changes how you look at things and how you feel about things. I like to think of myself as an artist — but now I'm working for my kid," he said. "Now I'm a father. I've got a lunch pail, I go to work and I come home and I make sure my kid is taken care of, and I make sure my wife is take care of."
The couple married in 2004.