Walter R. Bloor was born in Ingersoll, Ontario, Canada. After graduating from high school, he taught at a rural school for 2 years and then attended Queen's College (now Queen's University) in Kingston, Ontario. He graduated in 1902 with an M.A. and went to the State College of Washington in Pullman, Washington, to be an instructor in chemistry. In 1906, Bloor began graduate work at Harvard University with Otto Folin. After Bloor received his Ph.D. in 1911, he spent 4 years at Washington University in St. Louis and then returned to Harvard where he remained until 1918, when he accepted a position as professor of biochemistry at the University of California, Berkeley. In 1922, Bloor moved to the University of Rochester, where he became professor of biochemistry and associate dean in the new School of Medicine and Dentistry. He retired in 1947 but continued to work in his laboratory at Rochester.
While at Harvard with Folin, Bloor studied fatty substances and soon became a well-established pioneer in the investigation of fats in human nutrition. Among his many accomplishments in the study of lipids was the development of micro methods for lipid analysis, which opened up the field of lipid metabolism to quantitative study. Bloor was president of the American Society of Biological Chemists from 1929 to 1930 and was also chairman of the Executive Committee of the Federation of American Societies for Experimental Biology in 1931. In 1945, Queen's University awarded Bloor with an honorary degree.