Sharon Yvonne Stone was born in Meadville, Pennsylvania, to Dorothy Marie (née Lawson; b. 1933), an accountant, and Joseph William Stone II (1930–2009), a tool and die manufacturer and factory worker. She has a sister, Kelly, and two brothers, Michael and Patrick Stone. She is of part Irish ancestry. Stone was considered academically gifted as a child and entered the second grade when she was five years old.
She graduated from Saegertown High School in Saegertown, Pennsylvania in 1975. While attending Edinboro University of Pennsylvania, Stone won the title of Miss Crawford County, Pennsylvania and was a candidate for Miss Pennsylvania. One of the pageant judges told her to quit school and move to New York City to become a fashion model. In 1977, Stone left Meadville, moving in with an aunt in New Jersey. She was signed by Ford Modeling Agency in New York City. Stone, inspired by Hillary Clinton, went back to Edinboro University to complete in her degree in 2016.