[2] Citing his "outstanding and pioneering contributions to biomedical sciences and enzymology," the Wolf Foundation awarded Hayaishi the 1986 Wolf Prize in Medicine "for his discovery of the oxygenase enzymes and elucidation of their structure and biological importance".

[3][4] Hayaishi was President of International Union of Biochemistry and Molecular Biology from 1973 to 1976.

After serving as a medical officer in the Japanese Navy for three years, he joined the Institute of Microbial Diseases, Osaka University and was awarded his Ph.D. in 1949.

After working with Arthur Kornberg at the National Institute of Arthritis and Metabolic Diseases, National Institutes of Health and Washington University in St. Louis, Hayaishi served as a research group leader or a professor at various research institutions in the US and Japan including Kyoto University, and led approximately 600 graduate students in his life including Yasutomi Nishizuka; Tasuku Honjo, the 2018 Nobel laureate in medicine or physiology; and Shigetada Nakanishi.

[7] Hayaishi was awarded several honors, including the Asahi Prize (1964), the Japan Academy Prize (1967), the Order of Culture (1972), the Louis and Bert Freedman Foundation Award from the New York Academy of Sciences (1976), the Wolf Prize in Medicine (1986), and the Distinguished Scientist Award of the World Federation of Sleep Research Societies (1999).