Afar sano ka dib, Choi wuxuu u qalmay laba dhacdo oo dabaasha ah Ciyaaraha Olombikada Xagaaga ee 2012 ee London isagoo tirtiray FINA A-ta caadiga ah ee waqtiga gelitaanka ee 2:13.00 (200 m shakhsi ahaaneed) iyo 2:08.81 (200 m balastar) laga soo bilaabo FINA World Championships ee Shanghai, Shiinaha. Tartanka 200 m ee shakhsiga ah, Choi waxay ku dhameysatay kaalinta afaraad ee kaalinta lixaad iyada oo 0.19 ilbiriqsi ay ka dambeeyeen Great Britain's Sophie Allen, iyada oo hoos u dhigtay waqtigeeda Olombikada illaa 2:14.91. Waxay gashay kaalinta afar iyo labaatanaad ee heerarka hordhaca ah, mana aysan sii gudbin heerarka semi-finalka. Si ka duwan Olombikadeedii hore, Choi waxay diiwaangelisay waqtigii tobnaad ee ugu dhakhsaha badnaa ee 2:08.45 ee 200 m balastar
si ay u xaqiijiso kaalinteeda semi-finalka ciyaaraha isreebreebka subaxnimo. Choi waxay ku guuldareysatay inay u soo baxdo finalka, maadaama ay ku dhameysatay orodka semi-final iyada oo leh waqtiga saddexaad ee ugu hooseeya ee 2:08.32.