Born Betty Jean Jennings, Bartik was raised in rural Missouri, and attended Northwest Missouri State Teachers College, receiving a math degree. Answering an Army advertisement in 1945 for recent mathematics graduates, Bartik left for Philadelphia and began working on the ENIAC project. She soon met her husband, engineer William Bartik, and was married in 1946.
After her work on the ENIAC, Bartik continued to work on computing. Joining John Presper Eckert and John W. Mauchly, she worked on the UNIVAC computer, which made its debut in 1951. Shortly after the UNIVAC, Bartik left the computing industry to raise her children, and resumed professional work in the computing field in 1967, where she remained until she was laid off until 1985. Facing age discrimination and unable to find a job in the computing field, Bartik decided to go into real estate, where she remained for the remainder of her life.
Bartik died on on March 23, 2011 of congestive heart disease.