Widely known for his rivalry with Ayrton Senna, Fullerton won the Karting World Championship in 1973 with Birel.

From 1978 to 1980, Fullerton competed for DAP as the teammate of Ayrton Senna; their fierce rivalry saw several 1–2 finishes in major competitions.

Upon retiring from karting in 1984, Fullerton became a driver manager, coaching 2010 junior direct-drive World Champion and Formula E World Champion Jake Dennis, two-time 24 Hours of Le Mans winner Allan McNish, two-time Indianapolis 500 winner Dan Wheldon, as well as Formula One drivers Paul di Resta and Anthony Davidson.

[2] At 16 years old, Fullerton qualified, but failed to be selected for the British team to compete in the Karting World Championship in 1969.

[4] That same year (1980) Fullerton passed Senna on the very last lap of the Final to win the prestigious Champions Cup race at Jesolo (near Venice) in Italy.

[4] At a press conference at the 1993 Australian Grand Prix, when asked which driver he had the most satisfaction racing against, Senna cited Fullerton.