The re-polished group's first CD single "U" was released on 7 June 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.
A few months before the debut of Super Junior 05, Choi made his first official media appearance with bandmate Han Geng as one of the runway models in a fashion show by Bum Suk.
Choi officially debuted as part of 12-member rotational project group Super Junior 05 on 6 November 2005 on SBS's music program Popular Songs, performing their first single, "Twins (Knock Out)".
In March 2006, SM Entertainment began to recruit new members for the next Super Junior generation.
And if he still does not fully support gay rights so damn what??
Its his own opinion, and i really cant stand it when he gets hate (YES unlike what you said, he actually gets alot of backlash) just for voicing that out.
In 2006, Siwon was cast in the Hong Kong epic film A Battle of Wits, playing the role of the Liang Prince. The same year, he starred in his first taiwanese drama Skip Beat! The series is a live-action adaptation of Japanese shōjo manga Skip Beat! On 30 September 2017, an untied French bulldog owned by Choi's family bit their neighbor, 53-year-old businesswoman Kim who runs Hanilkwan, an upscale Korean cuisine restaurant.
This resulted in the death of the victim 6 days after the incident.