Willy Cahill began his martial arts education under his father, Professor John Cahill Sr., who founded Cahill's Judo Academy in Daly City, California, in 1948. Professor Cahill was one of the most highly respected instructors ever to come out of Professor Henry S. Okazaki's Kodenkan System of Jujitsu in Hawaii. In 1962, Professor Cahill passed away at a very young 50 years of age. In 1963, Willy built the new dojo in San Bruno, California, in his father's honor. At this club, Cahill set new standards and goals for himself and his students.

Over the past 40 years of working with men and women of all ages, Cahill has produced over 1000 national and international medal winners. Willy's elite athletes have represented the United States at numerous domestic and international events.

Cahill has dedicated his life in training individuals for the challenges of life through the sport of Judo and Martial Arts. He is known worldwide and previously as the Judo Coach for:

Stanford University
SF State University
US Coach of the Junior Pan American Championships
US Olympic Coach
US Coach Goodwill Games
Black Belt Hall of Fame Judo Instructor of the Year
Jujitsu American Hall of Fame Instructor of the Year