Bello was born in Norristown, Pennsylvania, the daughter of Kathy, a teacher and school nurse, and Joe Bello, a contractor. Her father is Italian American and her mother Polish American. She grew up in a working-class Roman Catholic family and graduated from Archbishop Carroll High School (Radnor, Pennsylvania). Later she attended Villanova University, majoring in political science. She intended to become a lawyer, but took an acting class during her senior year, just for fun. She was soon cast in small off-Broadway plays, such as The Killer Inside Me, Small Town Gals With Big Problems and Urban Planning. She later guest-starred on episodes of The Commish (1991), Nowhere Man (1995), Misery Loves Company (1995) and Due South (1994).