In 1986, her older brother Jason died of injuries suffered in a car accident, after being thrown from the back of a pickup truck while out for lunch with some of his high school classmates.
Katherine Heigl je živela v Virginiji in nato Denverju, preden se je družina ustalila v Connecticutu, kamor so se priselili v veliko, staro, viktorijansko kmetijo v bogato mesto blizu New Canaana, kjer je preživela večino svojega otroštva.