Born Sharon Forsmoe in Sioux City, Iowa, she made her acting debut in the 1959 film Kiss Her Goodbye. Throughout the 1960s and 1970s, Farrell appeared in such films as The Reivers, Marlowe, It's Alive, Night of the Comet, The Stunt Man, Out of the Blue, and Can't Buy Me Love. In addition to film work, Sharon also appeared in guest roles on various television shows including Death Valley Days and Hawaii Five-O.