Kertész coached several clubs in Germany, like Victoria Hamburg and Union Altona, and in other countries such as France and Scandinavia during the 1920s. He managed Swiss side FC Basel between 1928 and 1930. In January 1931 he took over at Hamburger SV where he successfully revamped the team, adding Rudolf Noack and other promising new players until he was appointed by VfB Leipzig in the summer of 1932. After his contract had been dissolved on a mutual agreement in May 1933, Kertész left Germany and emigrated to the USA where he worked in the record industry. His son, who called himself George Curtiss, was a leading manager at Remington Records.