2000–2007: Career beginnings Choi was initially discovered through an
SM Entertainment Open Audition when she was in fifth grade. She later won first place at the 2002 Korea-Japan Ultra Idol Duo Audition and debuted in Japan as a member of
Route 0. The duo released three singles before disbanding in 2003. Choi returned to SM Entertainment and eventually debuted in South Korea as a member of the girl group
Girls' Generation in August 2007.
2008–2016: Acting roles and songwriting Girls' Generation gained significant popularity with the release of their hit single "
Gee" in 2009. Choi has said in an interview that she was also interested in acting before debuting as a singer and had failed more than 70 auditions during her pre-debut days. Aside from Girls' Generation's activities, Choi has participated in various music and acting projects. In the early days, her acting work mostly involved several small roles and guest appearances—these include
KBS2's sitcom
Unstoppable Marriage (2007), romantic comedy film
Hello, Schoolgirl (2008), SBS's drama
Oh! My Lady (2010), SBS's
Paradise Ranch (2011) and SBS's ''
A Gentleman's Dignity'' (2012). During this period, musically, she recorded two songs—one trot song titled "KKok" with Girls' Generation member
Yuri for the
SBS' drama
Working Mom, while the other one, "Feeling Only You", was a collaboration with Girls' Generation member
Tiffany and South Korean duo The Blue. Throughout her career, besides contributing her vocals to Girls' Generation's songs, Choi has explored songwriting. She penned the lyrics for three songs: "
How Great is Your Love" (2011), "
What Do I Do" (2016), and "Sailing (0805)" (2016), while co-writing the song "
Baby Maybe" (2013). In September 2012, she landed her first major acting role in
tvN's medical drama
The Third Hospital. She was praised by both co-actors
Oh Ji Ho and
Kim Seung-woo and the viewers were drawn to her emotional scene due to her natural display of emotion. In May 2013, Choi was cast in tvN's romantic comedy drama,
Dating Agency: Cyrano. It was a spin-off of the 2010 movie
Cyrano Agency. She played a dating expert who works at a dating agency helping people to find their love. Park Ju-yeon from the
Hankook Ilbo praised Choi for her lively character portrayal and said that there was not any "overdone emotions commonly appear in acting newcomers". In September 2014, Choi scored a lead role in
MBC's melodrama,
My Spring Days. Her character is a terminally ill patient who gets a heart transplant; and meets her donor's husband, played by
Kam Woo-sung. This was a breakthrough performance for Choi as she won the "Best Actress in a Miniseries" award at the 2014
MBC Drama Awards and the "Excellence Award for Actress" at the 2015
Korea Drama Awards. In 2015, Choi starred as the female lead in KBS2's special drama
Perfect Sense, which was produced by
Samsung Fire & Marine Insurance to help raise public understanding of the disabled. She played a teacher named Ah-yeon who is visually impaired. In June 2016, Choi starred as the female lead alongside
Ma Dong-seok and
Seo In-guk in the OCN crime drama
Squad 38.
2017–present: Label change and continued acting In early August 2017, Choi starred as television producer in the
JTBC web drama
Someone You Might Know. Later in August, she played the female lead in the MBC drama series
Man in the Kitchen. In November 2017, Choi joined Echo Global Group after her contract with SM Entertainment ended. With a change of label, her future activities with Girls' Generation remain in discussion. In 2018, Choi was cast in the Korean-Japanese film
Memories of a Dead End and the action comedy film
Miss & Mrs. Cops. In December 2018, Choi released her solo single, "Winter Breath", which is her first song to be released since her departure from SM Entertainment, with the song's music video made available online on the same day. Choi launched her official Twitter and YouTube accounts to commemorate the single's release. In May 2019, Choi signed with new agency Saram Entertainment. In February 2020, Choi starred in the
OCN drama
Tell Me What You Saw. In 2020, Choi starred in JTBC romance drama
Run On. Then in 2021, she starred alongside
Choi Tae-joon in the
Naver TV romantic comedy series
So I Married the Anti-fan, based on the
manhwa of the same name and appeared in the
Netflix original series
Move to Heaven. In 2022, she starred in the KBS2 drama
If You Wish Upon Me in the role of a nurse at
hospice. Choi participated in Girls' Generation's fifteenth anniversary album
Forever 1 (2022), with her co-writing the songs "Seventeen" and "Villain" for the album. On August 29, 2024, Saram Entertainment announced that Choi would be releasing her Japanese debut
maxi single titled "Unstoppable" on October 30. In 2025, Choi starred opposite
Kim Jae-yong in the
ENA romance drama
I Dol I. She played Maeng Se-na, a lawyer and boy group fangirl. ==Personal life==