The South Korean baritone studied singing with Kwangdong Kim at Yonsei University in Seoul. During his studies, he took part in several masterclasses with Helmut Deutsch, Hong Hye Kyung and Samuel Youn, among others. In March 2015, he was also among the finalists in the JoongAng Music Concours competition.

Insik Choi has already appeared on opera stages in South Korea in roles including Conte Almaviva in Mozart's „Le nozze di Figaro“, Marcello in Puccini's „La Bohème“ and the Mandarin in „Turandot“, among others. In summer 2018, he took third place at the Ópera de Tenerife international singing competition and also won the audience prize. In 2023, Insik Choi won first prize and the audience prize at the Vincerò World Singing Competition in Verona.

From 2015 to 2017, he was a member of the International Opera Studio at Cologne Opera, and has been a member of the Cologne Opera ensemble since the start of the 17/18 season. He made his house debut as the Chamberlain in Stravinsky's „The Nightingale“, followed by his interpretation of Prince Tarquinius in Benjamin Britten's „The Rape of Lucretia“. Other roles include the title role in Purcell's „King Arthur“, several roles in „Die Heinzelmännchen zu Köln“, the King in Orff's „Die Kluge“, the Phantom in „Hoffmann's Tales for Children“, Marcello in „La Bohème“, Don Fernando in „Fidelio“, Baron Douphol in „La Traviata“, Monsieur de Brétigny in Jules Massenet's „Manon“, Heger in „Rusalka“, Orphée / Violin Teacher in „Je suis Jacques“ and the Mandarin in „Turandot“.

His recent roles in Cologne have included Wotan in „Der Ring des Nibelungen für Jung und Alt“, also as part of the Cologne Opera's guest performance in South Korea, Wiedehopf in Braunfels' „Die Vögel“, der König in „Die Kluge“, Der Heger in „Rusalka“, Escamillo in „Carmen“, Chorèbe in „Les Troyens“, Marcello in „La Bohème“, Lord Enrico Ashton in „Lucia di Lammermoor“, the One-Eyed Man in „Die Frau ohne Schatten“, Orest in „Elektra“, Marcello in „La Bohème“, Belcore in „L’elisir d’amore“ and Zurga in „Les pêcheurs de perles“. He also took on this role in a concert performance with the Antonio Vivaldi Orchestra in Italy. At the Korean National Opera, he sang Frank in „Die tote Stadt“.

During the 25/26 season, Insik Choi sang the roles of Lescaut in „Manon Lescaut“, Peter/Besenbinder in „Hänsel und Gretel“, Don Carlos in „Ernani“ and Ping in „Turandot“ at the Cologne Opera.

In the 26/27 season, he will appear as Lindorf / Luther / Coppélius / Miracle / Dappertutto in Stefan Herheim’s production of Jacques Offenbach’s „The Tales of Hoffmann“. He will also portray Alberich in Richard Wagner’s „Siegfried“, part of Paul-Georg Dittrich’s new Cologne „Ring“ cycle. In Giuseppe Verdi’s „Macbeth“, he will sing the title role in Damiano Michieletto’s acclaimed 2018 production, which was celebrated at Teatro La Fenice. In addition, he will perform the title role in Giuseppe Verdi’s „Rigoletto“.