The Budokwai (The Way of Knighthood Society) (武道会, Budōkai, Society of the Martial Way) in London is the oldest Japanese martial arts club in Europe. It was founded in 1918 by Gunji Koizumi and initially offered tuition in jujutsu, kendo, and other Japanese martial arts. It was the first judo club in Europe.

The full name of the society is the Budokwai (The Way of Knighthood Society) but it is normally called The Budokwai. The name Budokwai was chosen by the society's founder Gunji Koizumi as a combination of the Japanese words bu (武) meaning military or martial, do (道) meaning the way or code, kwai (会) meaning public building or a society/club. This translates into English as Society of the Martial Way.