Katic was born in Hamilton, Ontario, Canada to a Serbian father and Croatian mother, who both immigrated from Croatia. Her father is from Vrlika, and her mother is from the surrounding area of Sinj. Katic later moved with her family to Aurora, Illinois. She spent the following years moving back and forth between Canada and the United States. After graduating from West Aurora High School in 1996, she studied acting at Chicago's Goodman School of Drama. She has four brothers and one sister.
Blessed/cursed as a human transmitter and receiver capable of intercepting all kinds of electronic signals, Katic's imposing alter ego was also a whiz with firearms. But she gained greater recognition beginning in 2009, as Kate Beckett in the ABC series Castle, a Moonlighting-esque drama in which Katic's straightlaced homicide detective trades barbs and one-liners with Nathan Fillion's mystery novelist Richard Castle.
She has also made a name for herself by offering up scene-stealing work in such films as 2007’s Feast of Love and 2008’s The Spirit. She can currently be seen in a starring role opposite Nathan Fillion on the ABC series Castle, as well as alongside Kelly Hu and Dominique Swain in the forthcoming thriller Stiletto.