Holmes was born on December 18, 1978 in Toledo, Ohio. She is the youngest of five children born to Kathleen (née Stothers), a homemaker and philanthropist, and Martin Joseph Holmes, Sr., an attorney.

She has three sisters and one brother: Tamera, Holly Ann, Martin Joseph, Jr., and Nancy Kay. Holmes was baptized a Roman Catholic and attended Christ the King Church in Toledo. She graduated from the all-female Notre Dame Academy in Toledo (also her mother's alma mater), where she was a 4.0 student.

Katie Holmes' Family Tree