Some sources say that the founder of Hapkido, Choi, Yong Sul was a house boy/servant (some even say "the adopted son") of Japanese Daito Ryu Aikijujutsu GrandMaster Takeda, Sokaku. In Japan, Choi used the Japanese name Yoshida, Tatsujutsu since all immigrants to Japan took Japanese names at that time. Choi's Japanese name has also been given as Asao, Yoshida by some sources. According to this view, Choi studied under Takeda in Japan from 1913, when he was aged 9, until Takeda died in 1943. However, Daito Ryu records do not reflect this, so hard confirmation has not been available. Some claim that Choi's Daito Ryu training was limited to attending seminars.

Morihei Ueshiba, the founder of Aikido, was also a student of Takeda (this is not disputed). Hapkido and Aikido both have significant similarities to Daito Ryu Aikijujutsu, so it would seem that Hapkido's link to it is real, regardless of how and where Choi was trained.

Choi returned to Korea after Takeda's death and began studying Korean arts and teaching Yu Sool or Yawara (other names for jujutsu), eventually calling his kwan ("school") the Hapki Kwan. Ji, Han Jae, began studying under Choi and eventually started his own school, where he taught what he called Hapkido, after the grandmaster's school. Along the way, Hapkido adopted various techniques from Tang Soo Do, Tae Kyon, and other Korean kwans (schools).

Korean sources may tend to emphasize the Korean arts lineage of Hapkido over the Aikijujutsu lineage, with some even omitting the Aikijujutsu connection. However, as noted above, the connection can be seen in the techniques.

Ji now calls his system Sin Moo Hapkido. He currently lives and teaches in California, as does another former Choi student, Myung, Kwang Sik, who is GrandMaster of the World Hapkido Federation.

Some other Choi Hapkido students are still living. Chang, Chun Il currently resides in NY, and Im, Hyon Soo who lives and teaches in Korea. Both of these men were promoted to 9th dan by Choi. One of the first Hapkido masters to bring the art to the western culture was Han, Bong Soo. 

In the 1970's and 80's Hapkido was taught as the style of choice to elite South Korean armed forces units.

Although Hapkido contains both outfighting and infighting techniques, the goal in most situations is to get inside for a close-in strike, lock, or throw. When striking, deriving power from hip rotation is strongly emphasized.

Advanced students add a few more strikes and kicks as well as many more throws, locks, and pressure points. There is also some weapons training for advanced students - primarily belt, kubatan, cane, and short staff.

Some schools do forms, some do not. Some do sparring and some do not, although at the advanced levels, most schools do at least some sparring. Many Hapkido techniques are unsuitable for use in sparring, as their use would result in injury, even when protective gear is used. Thus, sparring typically uses only a limited subset of techniques.

There is generally an emphasis on physical conditioning and exercise, including "ki" exercises.