Knut Gjerset was born at Fræna in Møre og Romsdal, Norway. He was the son of Ole Sørensen Gjerset and Karen Marie Olsdatter Eidem. He immigrated with his family to Chippewa County, Minnesota during 1871. His brother, Oluf Gjerset, was an elected official in Minnesota.
Gjerset attended Willmar Seminary in Willmar, Minnesota and received his Bachelor of Arts degree in literature from the University of Minnesota in 1893. He held the position of principal at St. Ansgar Seminary in St. Ansgar, Iowa (1893-1895). He was married in 1894 Helen Baumgarten (1866-1966) at New Richland, Minnesota. Gjerset studied at Johns Hopkins University in Baltimore, Maryland (1895-1896) and at the University of Heidelberg (1896 to 1898) where he was awarded a PhD. 
Gjerset next worked as a principal at Glenwood Academy in Glenwood, Minnesota. In 1902, he became a professor at Luther College. Gjerset was department head of the history department for more than thirty years and co-editor of the literary yearbook Symra (1905-1914). He served as curator of the Norwegian-American Historical Museum.He published a number of historical works, including History of the Norwegian People (1915) and History of Iceland (1924). Knut Gjerset was appointed Knight of the 1st class in the Order of St. Olav in 1917. He also served as the chairman of the committee on exhibits for the Norse-American Centennial in 1925.  
- English Grammar (1908)
- Brændevinssamla gene og avholdsarbeidet i Norge (1911)
- History of the Norwegian People. Two Volumes (1915)
- Luther College Museum (1923)
- John Martin Kalberlahn (1924)
- History of Iceland (1924)
- Health Conditions and the Practice of Medicine Among the Early Norwegian Settlers, 1825-1865. with Dr. Ludvig Hektoen (1926)
- Norwegian-American Studies and Records. with Theodore C. Blegen, Kristian Prestgard, and Laurence M. Larson (1927)
- Norwegian-American Historical Museum (1929)
- Norwegian Sailors on the Great Lakes (1933)
- Knut Gjerset (David T. Nelson Volume 25: Page 27, The Norwegian-American Historical Association)
- Knut Gjerset (Store norske leksikon)
- Knut Gjerset. "A Norwegian-American Landnamsman: Ole S. Gjerset". The Norwegian-American Historical Association. Retrieved November 3, 2015.
- Knut Gjerset Collection (Luther College)
- "Gjerset, Knut" at the Wayback Machine (archived August 15, 2009), Christian Cyclopedia. The Lutheran Church--Missouri Synod.
- April Schultz, The Pride of the Race Had Been Touched: The 1925 Norse-American Immigration Centennial and Ethnic Identity," The Journal of American History, March 1991, 1265-1295.
- Knut Gjerset (Norsk biografisk leksikon)
- Luther College Faculty (1922) Luther College Through Sixty Years 1861-1921 (Minneapolis: Augsburg Publishing House
- Norlie, Olaf (1925) History of the Norwegian People in America (Minneapolis: Augsburg Publishing House)