While on vacation in Italy the True Blood heartthrob, 33, popped the question to his girlfriend, actress/model Audra Marie, his rep tells PEOPLE.
Manganiello, who plays werewolf Alcide Herveaux on the HBO drama, and Marie met at a 2009 Super Bowl party, but it was anything but love at first sight.
"She wouldn't go out with me for six months," Manganiello told PEOPLE in September. "We started dating a few months before I got cast [on True Blood]."
Manganiello says Marie is "a great dresser. She's gorgeous, and she's tall. And she's sweet ... nice. And she makes crazy English breakfasts."
Marie, meanwhile, says her man’s most appealing qualities are his "sense of humor, his work ethic and how humble he is with everything that has gone on."
The pair have not yet set a wedding date.