Madison, who has been dating 38-year-old party promoter Pasquale Rotella for about nine months, is 12 weeks pregnant, UsMagazine.com reported Wednesday.
"I've always wanted to be a mom," Madison, 33, told the magazine. "But I thought it would take longer!"
Madison is best known as one of Playboy founder Hugh Hefner's girlfriends, who were featured on the reality television series "The Girls Next Door." She also starred in her own reality series "Holly's World."