Waldemar Bernatzky won his first cycling race in 1933 and went on to win more than 250 races across Uruguay and South America. In 1947 Bernatzky became the American road race champion in Santiago, Chile, and won a pre-Olympic selection event for the 1948 London Games. At the Olympics he competed in the road race but did not finish the course. He had better success on the track, finishing fourth in the 4,000 metres team pursuit after Uruguay lost to Great Britain in the medal race for bronze. Bernatzky also competed in the road race at the 1948 World Cycling Championships in the Netherlands.