Randall was educated at Lasswade High School, Midlothian, and the University of Edinburgh, where he completed a degree in Physical Education.[3] In 1996, he was selected for Great Britain to compete at the Olympic Games in Atlanta, Georgia. Competing in the -78kg division, he lost his first round match and failed to progress any further. The following year in 1997, he finished fifth at the 1997 World Judo Championships.[1]
In 1996, he won his first Scottish National Championship and in 1998 he became champion of Great Britain, winning the half-middleweight division at the British Judo Championships.[4] The following year in 1999 he won a world title after winning the gold medal in the 81 kg division at the 1999 World Judo Championships.[1]
The 1999 success made him a certain selection for the 2000 Olympic Games in Sydney. He fought in the -81kg division but was eliminated in his second match.[1] In 2001, he won his second British Championship and third Scottish national title.[4] At the 2002 Commonwealth Games in Manchester, representing Scotland he claimed the gold medal in the -81 kg division.
Randall was inducted into the Scottish Sports Hall of Fame in March 2010.[5] He was the second male from Great Britain to hold a world title in judo. He was also seen in the STV series of Coached Off The Couch.