Fredericks won silver medals in the 100m and 200m in the 1992 and 1996 Olympics. He won gold medals at the World Championships and World Indoor Championships. He used to be the 200m world record holder, and is still the 200m indoor record holder. He finished 4th at the 2004 Olympics, even though he was 36 years old.
After the 2004 Olympics, he retired and became a member of the International Olympic Committee. He is the only person from Namibia to medal at the Olympics. He has also ran the 200m in less than 20 seconds more times than anyone else.