The New Year's Eve ceremony took place a year and a half after Harris first broke off the engagement, The Hollywood Reporter said.
"Today is the day I become Mrs. Hugh Hefner. Feeling very happy, lucky, and blessed," Harris, Playboy's Miss December 2009, tweeted.
Hefner, 86, and Harris, 26, originally were to be married in June 2011, but Harris called it off five days before the big day, saying on her website: "After much deep reflection and thought I have decided to end my engagement with Hef. I have the utmost respect for Hef and wish him the best going forward."
The pair reunited earlier this year, with Harris showing off her new engagement ring on Twitter. She auctioned off her first ring, which featured a 3.39-carat circular-cut diamond, in October, THR said.