According to Paul Maslak in the November, 1984 issue of Official Karate Magazine, Jackson originally received his black belt in Tang Soo Do from Harold Williams.
In 1973 he won every major tournament on the karate circuit making him the sport's biggest money-winner on record at that time, as well as being the first African-American fighter to be ranked number one in the United States.
In 1974, The California Flash, as Jackson was nicknamed, was invited to participate in the first PKA world Full-contact championship promoted by Mike Anderson and Don and Judy Quine.
Jackson, as well as his fellow Americans, was the overwhelming favorite in the Light-Weight division, where he fought Dominican Tae-Kwon-Do fighter, Ramón Smith, who had been invited to the tournament with a two-week notice as a replacement for Mexican José Luis Olivares.
In kickboxing, Jackson defeated among others, Ricci Wynn, Miguel Sanders, Sam Montgomery, Ray McCallum, Jerry Galarza, Tabata, and Toshio Arima to become the 1980 number one world contender in both the WKA and the PKA.