Aikido was founded by Morihei Ueshiba (1883 - 1969), known to all aikidoka (practitioners of aikido) as "O-Sensei" (Great Teacher). As a young man, Ueshiba trained in many forms of martial arts, always striving to increase his ability and to become stronger. At the same time he was drawn to various ascetic and spiritual practices. At one point after easily defeating an army officer who challenged him with a wooden sword while he himself was unarmed, Ueshiba had an enlightenment experience in which he felt himself to be one with the universe. Out of this experience emerged a new art which Ueshiba named "Aikido," which means "the way of harmony with universal energy."

Ueshiba felt that the very desire to attack breaks the harmony of the universe and is therefore a weakness. He believed that that the true aim of the martial arts should be protection, not destruction. "True budo (martial arts) is love," he said, and that meant that one should even try to protect one's attacker. This is a truly radical shift in martial arts philosophy. Because of this emphasis on protection, Aikido offers the possibility of 'polishing one's ego,' changing how one views and responds to conflict.

Before World War II, Aikido was practiced by only a few people. One needed an introduction even to be considered for admittance as a student. But with the lesson of war fresh in his mind, Ueshiba opened the practice of Aikido to the general public in the late 1940's, hoping that his art might help to contribute to greater social and personal harmony. Since then, Aikido has spread throughout the world. In the United States, there are now Aikido schools in every state and major city.