Gábor Benedek learned the essentials of modern pentathlon in military school and specialized in fencing. He served during World War II and was a prisoner of war for some time, but survived the conflict and made the Hungarian national team in 1948. He did not attend that year’s Olympics, but debuted instead in 1952, where he took silver in the individual competition. With his teammate István Szondy capturing bronze, Aladár Kovácsi’s 12th place finish was sufficient for the Hungarians to win gold in the team competition. Benedek returned in 1956 with János Bódy and Antal Moldrich, finishing sixth individually and fourth as a team.
Benedek was also the individual winner at the 1953 World Championships and part of the gold medal-winning Hungarian team in 1954 (with Szondy and non-Olympian Károly Tasnády). Individually, he won bronze medals at the 1947, 1949, 1950, and 1956 Hungarian Championships and was runner-up in 1951. He was a four-time national champion in the team event (1949, 1951-1953), once runner-up (1950), and once bronze medalist (1956). He also won a Hungarian team fencing championship in 1951. He continued to compete for several years after Melbourne, but was banned from further participation for political reasons in 1959. He later became a coach and eventually emigrated to West Germany, where he remained until the collapse of the Soviet Union.