Jung qualified for two swimming events at the 2012 Summer Olympics in London, by eclipsing FINA B-standard entry times of 2:02.50 (200 m individual medley) and 4:18.98 (400 m individual medley) from the FINA World Championships in Shanghai, China. In the 400 m individual medley, Jung challenged seven other swimmers on the second heat, including two-time Olympian Raphaël Stacchiotti of Luxembourg. He clinched a fifth spot and twenty-eighth overall by six hundredths of a second (0.06) behind Belarus' Yury Suvorau and Portugal's Diogo Carvalho, outside his entry time of 4:23.12. In his second event, 200 m individual medley, Jung edged out Ukrainian swimmer and double European junior champion Maksym Shemberev of Ukraine to claim a heat one victory by 0.07 of a second, with a time of 2:03.33. Jung failed to advance into the semifinals, as he placed thirty-second in the preliminary heats.