When Hannah was only twelve years old, she took a train to Fergus Falls, Minnesota, where she was taken in by the family of a local milkman. There Hannah attended Fergus Falls High School, and then enrolled at Park Region Luther College, where she graduated at the age of 17. After she earned her teaching certificate, Hannah taught from 1898 to 1908 at a small rural schoolhouse. She married farmer Charles Taylor Kempfer in 1903, and although the couple never had any children of their own, they fostered eleven orphans.
In 1923, Hannah was elected to the Minnesota House of Representatives, where she served from 1923 to 1930 and 1933 to 1942. She was one of four women elected to the Minnesota House following the passage of women's suffrage. She is best known for championing the causes of children, the conservation of natural resources, and the official selection of the Showy Ladies' Slipper as Minnesota's state flower.
Hannah Jensen Kempfer is remembered today as a true chalkboard champion.