Hwang took Taekwondo lessons from age 14 and achieved his 7th dan (rank) black belt. In 1965 at age 21, Hwang became a martial arts instructor for the Korean and South Vietnamese Armies, specializing in taekwondo. In January 2003, Hwang received his 9th dan black belt in taekwondo. In addition, he currently holds a 9th dan rank with the World Tang Soo Do General Federation.

In the mid 1970s, Hwang performed in two Jackie Chan movies Snake in the Eagle's Shadow and Drunken Master. as "Sheng Kuan" and "Thunderfoot" ("Thunderleg"). In 2002, Mike Leeder, a Writer and Producer, interviewed Hwang for the "Contender films" Hong Kong Legends DVD range.

Hwang began his acting career in Korean movies. In 1976, Ng See-yuen offered Hwang employment in Hong Kong. Hwang took the lead in many martial arts movies, usually playing a villain. The Secret Rivals was the first film where Hwang appeared as the "Silver Fox". Hwang's nicknames, "King of the Legfighters" and "Thunderleg" relate to his style of martial arts performance where he uses his legs in a particular way.

In 1981, Hwang directed his first movie, Hitman in the Hand of Buddha, and was credited as Wong Chin.

In 1989, taekwondo grandmaster Jun Chong invited Hwang to come to the United States to appear as a villain in the film Street Soldiers. To bring an international flavor to the film, Hwang is credited in the film as "Jason Hwang", named after his son. In the early 1990s, Hwang returned to South Korea, where he ran a golf-tee Manufacturing company and an hotel in Seoul. Later on, Hwang managed a bodyguard agency. Since then he has made only occasional film appearances, in movies such as Emperor of the Underworld (1994) and Boss (1996). In July 1996, Hwang retired from acting at the age of 51.