Born Marisa Bertetta in Santa Cruz, California, she was "discovered" at age 16 walking through a San Francisco café by two Italian modeling agents. After talking to her parents, Marc and Krista Bertetta, she was on a plane to Italy with her mom a few months later. Miller first gained attention when she appeared in a 1997 issue of Perfect 10 magazine. Although she came in third behind Ashley Degenford and Monica Hansen in Perfect 10 magazine's first annual model search, she was repeatedly showcased in following issues, including the covers of the Winter 1998, Aug/Sept 1999, and Fall 2004 editions. She has two sisters, Maleah and Alisha, and attended Monte Vista Christian School in Watsonville, California.