Choi was scouted by a talent agent from
SM Entertainment when he was 16 as he was waiting for friends in front of his high school. The agent recommended him to audition for the company's
Starlight Casting System. He auditioned without his parents' approval; his parents were notified only after he passed the auditions. Although his parents allowed him to sign a contract with SM Entertainment, they did not give him any help because they wanted him to take responsibility for his actions. He later moved into dormitories with fellow trainees and was trained in areas of singing, acting, dancing as well as languages. He was featured in a music video of
The Grace's
Dana whilst he was being trained as a solo singer in 2003. A year after, Choi made a brief appearance in family drama
Precious Family, and again in 2005 in the KBS romance comedy drama
Eighteen, Twenty-Nine as young Kang Bong-man, while in 2006 he played the supporting role of Park Sang-woo in romance melodrama
Spring Waltz.
Debut with Super Junior and Super Junior-M Not long after Choi's first television appearance, SM Entertainment released an announcement that he would debut as one of the twelve members in a boy band. A few months before the debut of Super Junior 05, Choi made his first media appearance with bandmate
Han Geng as one of the runway models in a fashion show by Bum Suk. Choi debuted as part of 12-member rotational project group
Super Junior 05 on November 6, 2005, on
SBS' music program
Popular Songs, performing their first single, "
Twins (Knock Out)". Their debut album
Twins was released a month later on December 5, 2005, and debuted at number three on the monthly MIAK K-pop album charts. In March 2006, SM Entertainment began to recruit new members for the next Super Junior generation. However, plans changed and the company declared a halt in forming future Super Junior generations. Following the addition of thirteenth member
Kyuhyun, the group dropped the suffix "05" and became officially credited as Super Junior. The re-polished group's first CD single "
U" was released on June 7, 2006, which was their most successful single until the release of "
Sorry, Sorry" in March 2009, which helped them achieve global success. In April 2008, Choi was put into seven-member sub-group
Super Junior-M, a
Mandopop subgroup of
Super Junior for the Chinese music industry. They debuted in China at the 8th Annual Music Chart Awards, simultaneously with the release of their first music video, "
U" on April 8, 2008. This was followed by the release of the debut Chinese-language
studio album,
Me in selected provinces in China on April 23 and May 2 in Taiwan. On July 5, 2023,
Super Junior-L.S.S., a sub-unit group consisting of Super Junior bandmates Choi,
Leeteuk, and
Shindong, debuted with their first Japanese single "/Shatta Shimero". The trio later made their official Korean debut on January 22, 2024 with the single "Suit Up".
Solo ventures In 2006, Choi was cast in the Hong Kong
epic film A Battle of Wits, playing the role of the Liang Prince. This also marks his film debut. Choi received praise from co-star
Andy Lau, who stated that Choi sets a good example for Hong Kong actors. In 2007, Choi starred in
Attack on the Pin-Up Boys along with other Super Junior members. The same year, he was cast in MBC's two-episode mini series
Legend of Hyang Dan. After a three-year hiatus, Choi returned to the screen with SBS' romantic comedy
Oh! My Lady. The same year, he starred in the big-budget spy series
Athena: Goddess of War, a spin-off to the 2009 hit drama
Iris. He plays a data analyst and rookie elite agent. In 2011, Choi headlined KBS' action drama
Poseidon. The same year, he starred in his first
Taiwanese drama Skip Beat! with
Ivy Chen and fellow band member
Donghae. The series is a live-action adaptation of Japanese
shōjo manga titled
Skip Beat! by
Yoshiki Nakamura. In 2012, Choi starred in SBS' comedy satire drama
The King of Dramas, based around Korean television production. He plays Kang Hyun-min, a top celebrity with a prickly personality. Choi starred in multiple projects in 2015. He co-starred in Hong Kong historical-action film
Dragon Blade with
Jackie Chan, crime thriller
Helios and sports drama
To the Fore alongside
Eddie Peng and
Shawn Dou. He also starred in the Chinese romance drama
Fall In Love With You Again and was cast in
Billion Dollar Heir, a Chinese adaptation of the 2013 hit drama
The Heirs. Back in Korea, Choi starred as the second male lead in MBC's romantic comedy
She Was Pretty. He received critical acclaim for his acting performance and comedic portrayal of the character, and experienced a rise in popularity. He released a single for the drama titled "Only You", which ranked atop the music charts. In 2015, Choi Siwon with EnterMedia Pictures (CEO Lee Dong Hoon) purchased the rights to the 2011
Daum webtoon
Interview, authored by Rude Vico. In October 2017, Choi starred in the tvN's youth romance drama
Revolutionary Love alongside
Kang So-ra. This marked his first project after releasing from his
mandatory military enlistment on August 18, 2017. In April 2019, Choi starred in KBS's crime comedy drama
My Fellow Citizens!. In 2020, he starred in an episode of the science fiction anthology series
SF8. In 2022, Choi starred in the
ENA romantic comedy series
Love Is for Suckers and returned for the second season of
Work Later, Drink Now. In 2023, Choi played a supporting role in the
Netflix original series
Bloodhounds, and made a cameo in the TVING original series ''
Death's Game. In 2024, he starred in the TV Chosun romantic comedy series DNA Lover''. ==Other ventures==