Rosman was born in Charleston, South Carolina and has some Cherokee Indian ancestry. In 1996, she got the part of Ruthie Camden on 7th Heaven, which she still plays today, in its tenth season. Rosman (along with Stephen Collins, Catherine Hicks, and Beverley Mitchell) has appeared in every episode of the series. In addition to her role on 7th Heaven, Rosman appeared in the independent film Gideon, starring Christopher Lambert, Charlton Heston and Shelly Winters. She has appeared in numerous television commercials starting at age four. She also played JonBenét Ramsey in Getting Away with Murder: The JonBenet Ramsey Mystery.

Her parents are divorced, and she resides in Los Angeles with her mother, step-father, younger brother Chandler (Born 1993) and older step-sister Katelyn Salmont (Born 1986). She is an active supporter for fundraising for the Cystic Fibrosis Foundation and wishes to help educate the public about the need for organ donation. Her stepsister Katelyn, who has CF, recently underwent a successful double lung transplant. Rosman and her family are grateful that 7th Heaven, in a past season, was able to produce an episode about CF, in which Katelyn was able to play herself.

Her greatest passion, outside of acting, is animals, especially horses, of which she owns three. She is a competitive equestrian show jumper, and recently competed in Belgium in her first international show. She and her family reside on a ranch outside of Los Angeles, where she keeps horses, dogs, cats, chickens and goats.