From 1923 onwards András Székely was a swimmer with the Tatabányai Bányász club and then from 1929 he swam for the Ferencvárosi Torna Club and played water polo player for BEAC. It is interesting that, although he did not win a single Hungarian championship, his international successes were significant.
From 1930 to 1934 he was a member of the national swimming team. At the 1932 Summer Olympics, he won a bronze medal as a member of the 4 × 200-meter freestyle relay. He had previously won the gold medal at the 1931 European Championships in Paris with the same relay. His performances in the World College Championships in Darmstadt in 1931 and 1933 in Turin earned him a total of eight medals, five gold, two silver and one bronze medal. One of the silvers came as a member of the Hungarian water polo team. András Székely attended the Technical University for two years, during the 1929/30 and 1930/31 academic years, but after that he stopped his studies here for unknown reasons. He ended his sporting career in 1936.
As a Jew, he was murdered by the Nazis in 1943 at the Chernihiv concentration camp, a labour camp in what is now Ukraine.