Democrat Maggie Hassan took the oath of office Thursday afternoon in Concord.
The 54-year-old business attorney from Exeter succeeds John Lynch. Lynch retired after four two-year terms.
Hassan beat out Republican Ovide Lamontagne in November to win the office.
It's a big year for women in politics in New Hampshire. In addition to the governor's seat, New Hampshire is sending an-all female delegation to Washington and has women serving as speaker of the House and chief justice.