Gregor Hradetzky was born into a family of organ builders. While learning in the factory of his father he also started canoeing at a relatively late age of about 17, but was also a multi-sport talent, who trained cross-country skiing and ski jumping. Soon after he won his first Austrian championship in canoeing and in 1934 he became European champion in folding K-1 10K, a title which he was able to defend in 1935. In 1936 he also tried to participate in the Winter Olympics, but a hand injury prevented him from competing in Nordic Combined.
At the 1936 Summer Olympics he became only the second (and last) Austrian to win two gold medals at the same Summer Games (after Julius Lenhart). Hradetzky won the K-1 1,000 and the folding K-1 10,000. After the “Anschluss” he had to compete for Nazi Germany at the inaugural World Championships held in Vaxholm in 1938 and won bronze in K-1 1,000 m. World War II ended his sporting career and when he returned from British war captivity in 1948 he took over the family business. He became an internationally known organ builder and his company installed organs in the United States, Japan, and also in Australia at the Sydney Opera House. In 1963 an organ was built in Tyrol and named “Olympiaorgel” (Olympia Organ) in honor to the 1964 Innsbruck Winter Olympics. In 1981 Hradetzky received the Olympic Order in Bronze. He died in 1984 during a holiday, but the family business still remains in the hands of his son.