Sooyoung was born in Gwangju, Gyeonggi, South Korea, on February 10, 1990. She is the younger sister of Choi Soo-jin, who is a musical theatre actress. Sooyoung 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.

Sooyoung returned to SM Entertainment and eventually debuted in South Korea as a member of the girl group Girls’ Generation in August 2007. The group gained significant popularity with the release of their hit single “Gee” in 2009. Sooyoung 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.

Sooyoung graduated from JeongShin Women’s High School in 2009. She went on to major in film studies and graduated from Chung-Ang University in February 2016, receiving a lifetime achievement award at the graduation ceremony. Her fellow Girls’ Generation member Kwon Yuri attended the same university.

Throughout her career, besides contributing her vocal to Girls’ Generation’s songs, Sooyoung has explored into lyrics writing. 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, Sooyoung 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 Sooyoung for her lively character portrayal and said that there was not any “overdone emotions commonly appear in acting newcomers”.

In September 2014, Sooyoung 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 Sooyoung 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. She contributed a song to its soundtrack, titled “Wind Flower”. In 2015, Sooyoung 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, Sooyoung starred as the female lead alongside Ma Dong-seok and Seo In-guk in the OCN crime drama Squad 38.

Since 2015, Sooyoung has held an annual charity auction event called “Beaming Effect”, to raise money for finding a cure for retinitis pigmentosa, a disease that her father suffers from.

In early August 2017, Sooyoung 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, Sooyoung 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, Sooyoung was cast in the Korean-Japanese film Memories of a Dead End, the action comedy film Girl Cops, and the romantic comedy television series So I Married an Anti-fan, based on the manhwa of the same name, alongside Choi Tae-joon.

In December 2018, Sooyoung 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. Sooyoung launched her official Twitter and YouTube accounts to commemorate the single’s release.

In May 2019, Sooyoung signed with new agency Saram Entertainment. In February 2020, Sooyoung starred in the OCN drama Tell Me What You Saw.