Hagan is the niece of former governor of Florida, Lawton Chiles. Her father Joe P. Ruthven was mayor of Lakeland, Florida. She studied at Florida State University and Wake Forest University law and worked as a lawyer. She is married to lawyer Charles T. "Chip" Hagan III and has three grown children.
Kay Hagan represented since 1998, the 27th electoral district in the Senate of the State of North Carolina. On 30 October 2007 she declared to run in 2008 for a seat in the Senate of the United States. In the election on November 4, 2008, they succeeded against her Republican predecessor Elizabeth Dole in the otherwise conservative state by. Hagan scored 52.7 percent of the vote, Dole 44.2 percent.