Kajukenbo was founded in 1947 at Palamas Settlement on Oahu, Hawaii. It developed out a group calling themselves the "Black Belt Society", which consisted of black belts from various martial arts backgrounds who met to train and learn with each other. This was the beginning of an evolutionary, adaptive style designed to combine the most useful aspects of the arts.
There are five men credited as founders of Kajukenbo, and it is from their respective arts that Kajukenbo draws it's name.

Kenpo emerged as the core around which this new art was built. Although uncreditted by name, other influences included American Boxing (Choo was Hawaiian Welterweight Champion) and Escrima (Emperado also studied Kali and Arnis Escrima).

In the late 1940's, Palamas Settlement was a violent area and fist-fights or stabbings were commonplace. From this environment, the founders of Kajukenbo wanted to develop an art that would be readily usefull on the street. As they trained and fought in and around Palamas Settlement, the founders of Kajukenbo quickly gained reputations as formidable street-fighters. In 1950, Adriano Emperado, along with brother Joe Emperado, began teaching the new art in an open class. They called the school Kajukenbo Self Defense Institute (K.S.D.I.).

The emphasis during training was on realism - so much so that students routinely broke bones, fainted from exhaustion, or were knocked unconcious. Nevertheless, the reputation of this tough new art drew more students and Emperado opened a second school at the nearby Kaimuki YMCA. Soon Emperado had 12 Kajukenbo schools in Hawaii, making it the second largest string of schools at the time. John Leoning, who earned a black belt from Emperado, brought Kajukenbo to the mainland in 1958. Since that time, Kajukenbo has continued to flourish and grow.