Greene was born in Jacksonville, Florida, the daughter of Michele, who works in insurance.....

Greene was born in Jacksonville, Florida, the daughter of Michele, who works in insurance, and Joe Greene, a U.S. Marine who now owns his own concrete business. She grew up in Middleburg and Jacksonville, and went to University Christian School before transferring to Wolfson High School when she was in tenth grade. She moved to Los Angeles, California, at the age of 17 to pursue an acting career.Greene has one sibling, an older brother named Joe, who still resides in Jacksonville with his parents.
Greene is good friends with her Twilight co-stars, particularly Kellan Lutz, whom she knew before filming the movie.

While shooting the latest installment of the Twilight saga, New Moon, Greene told USMagazine.com that "We were working 12 hours a day, so it didn't leave too much time to eat." To stay in shape Greene reportedly had a personal trainer on set, worked out for several hours each day and started doing Pilates to maintain her physique. Her trainer has also begun to teach the starlet mixed martial arts in preparation for the third movie in the Twilight series, Eclipse, slated for a 2010 release. "I get to fight in "Eclipse." My trainer is teaching me mixed martial arts right now. So. Cool. But I feel if I was in a real fight, I'd get my ass kicked.