After placing fourth in the individual event at the 1960 Summer Games, Balczó won team gold medal at the same year. In 1968, he won the silver medal in the individual event and gold in the team. In 1972, he won the individual title and a silver medal in the team event, for a total of five Olympic medals (three gold, two silver). Although the reigning world champion, he did not compete in the 1964 Games but his overall record is the greatest of any modern pentathlete. His best event was cross-country running. He was a professional typewriter mechanic.