Belli received a Bachelor's degree from Penn State. For many years she acted in musical theatre and soap operas in New York City, followed by a Los Angeles career producing and directing theatre with over 75 play productions to her name.

Belli made her television directorial debut on episode of Charles in Charge in 1988. Her other television credits include, Major Dad, USA High, Sister, Sister, One World, The Hughleys, One on One, Abby, Eve, Girlfriends, Living with Fran, The Game and Wizards of Waverly Place.

Belli is the co-author of two books: The Sitcom Career Book and Acting for Young Actors with actress Dinah Lenney and foreword by Jason Ritter. and The Sitcom Career Book with Phil Ramuno and foreword by Henry Winkler. She has also been a judge for the Miss America Outstanding Teen Pageant, a lecturer at the Chautauqua Institute, and a panelist for Women in Film, the Directors Guild of America, Screen Actors Guild, and the American Federation of Television and Radio Artists. She has judged the California Independent Film Festival, the Sapporo Short Film Festival in Japan, and CSU Media Arts Fest.

Among the awards she has won is from Mayor Tom Bradley for her work with abused children. She has lectured frequently throughout the United States including many universities such as AFI, New York University, Northwestern University, and University of Connecticut.

Belli currently lives in Los Angeles with her husband and two teenage children, who are both actors.