Katō attended the Tokyo University of Education (now University of Tsukuba). At the 1968 Olympic Games in Mexico City, he won a gold medal in the combined exercises and shared a gold as a member of the Japanese team. In addition, he won the gold medal in the floor exercise and won a bronze in the rings. At the 1972 Games in Munich, W.Ger., Katō won his second consecutive gold in the combined event, as well as a team gold, an individual gold in the parallel bars, and individual silver medals in the pommel horse and horizontal bars. Katō excelled at the 1976 Olympics in Montreal, leading the Japanese team to its fifth consecutive gold medal. He also won an individual gold medal in the parallel bars and a silver in the individual combined.

Katō was renowned for his self-discipline and dedication to the sport. He later became a lecturer at the University of Tsukuba and a coach; his student Tanaka Hikaru won the 1994 Japanese national championship. Katō was inducted into the International Gymnastics Hall of Fame in 2001.