Messing was born in the Brooklyn borough of New York City, the daughter of Sandra (née Simons), who has worked as a professional singer, banker, travel and real estate agent, and Brian Messing, a sales executive for a jewelry manufacturer. Messing is Jewish, a descendant of immigrants from Russia and Poland. When Messing was three, she moved with her parents and her older brother, Brett, to East Greenwich, a small town outside Providence, Rhode Island.

During her high school years, she acted (and sang) in a number of high school productions, including the starring role in the musical "Annie" and "Fiddler On the Roof". Messing took lessons in dance, singing, and acting. In 1986, she was Rhode Island's Junior Miss and competed in Mobile, Alabama in the America's Junior Miss scholarship program. While her parents encouraged her dream of becoming an actress, they also urged her to complete a liberal arts education before deciding on acting as a career. Following their advice, she