E wha nga tau i muri mai, Choi tohu mo te rua ngā hākinakina kaukau i te 2012 Summer Olympics i Rānana mā te whakakore FINA A-paerewa wāhi wā o 2:13.00 (200 m takitahi medley) me 2:08.81 (200 m butterfly) i te FINA World Championships i Shanghai, China. I roto i te 200 mita takitahi takitahi, ka mutu a Choi i te wera e wha i te tuaono o te 0.19 o te tuarua i muri i a Sophie Allen o Great Britain, ka whakaheke i tana waa Orimipia ki te 2:14.91. I whakanohoia e ia te rua tekau ma wha i roto i nga wera tuatahi, a kaore i eke atu ki nga haurua whakamutunga. Kaore i rite ki ana Olympics o mua, i tuhia e Choi te wa tere tekau o te 2:08.45 i te 200 mita butterfly
hei whakarite i tōna wāhi mō te haurua whakamutunga i ngā tukinga o te ata. Kaore a Choi i eke ki te whiringa toa, i te wa i mutu ai ia i te hawhe whiringa toa me te toru o nga waa iti rawa o te 2:08.32.