[10] In July 2016, Seulgi released "Don't Push Me" with bandmate Wendy as part of the soundtrack of the television series Uncontrollably Fond.

[12] On November 18, she sang the theme song of the MMORPG Blade & Soul, "You, Just Like That" (그대는 그렇게), although it was not officially released as a digital single until 2017.

[16] In March, Seulgi featured on labelmate Mark's "Drop", an original song performed on High School Rapper.

[18] The group, called Girls Next Door, released the song "Deep Blue Eyes" and held their debut stage at Music Bank on July 14.

[18] On October 27, Seulgi released a remake of the 2001 song "Doll (인형)", originally by Shin Hye-sung and Lee Ji-hoon, along with Kangta and Wendy as part of the second season of SM Station.

[29] On April 20, 2020, SM Entertainment confirmed that Seulgi would be part of Red Velvet's first sub-unit, alongside bandmate Irene.

The EP contained the studio version of Seulgi's solo song "Uncover", which was first revealed during Red Velvet's third concert tour La Rouge.

[34] On February 1, Seulgi and rapper Bewhy released a music video for the song "Born Confident" for a Volkswagen campaign.

[42] On September 13, 2022, it was announced that Seulgi would debut as a soloist with the release of her first EP, titled 28 Reasons, on October 4, led by the single of the same name.

[48] On April 3, 2024, another OST sung by Seulgi was released and dedicated to the famous Fu Bao panda, titled "You're My Joy and Luck (넌 기쁨이자 행운이야)".

[50] On January 15, 2025, the legend diva Kim Wan-sun collaborated with Seulgi for the digital release of the single "Lucky" produced by JYP.

[53][54] Brands often cite her positivity, creativity, passion for her craft, unique sensibility and style and cultural influence (especially among young Koreans) as reasons for why they choose her to represent them.

[59][60] She topped the monthly "Individual Girl Group Members Brand Power Ranking" published by the Korean Corporate Reputation Research Institute several times.

[61][62][63] In a survey among soldiers doing mandatory military service in South Korea in 2019, Seulgi ranked as the fourth most popular female K-pop idol.

[64] She has also consistently placed high in the Korea Queer Women Community's annual poll due to admiration for her "girl crush" image.

[69] In her show Seulgi.zip, a mainly fashion-themed program, Seulgi discussed fashion items, style points and favorite trends with her guests and gave advice to her listeners.

[57] Several days later, French retailer L'Occitane launched a new campaign featuring Seulgi as the ambassador for their OMY "City Palette" shea butter hand cream.

She served as the face of a new campaign for their new T-Roc model and helped promote it with original music and video for their slogan "Born Confident".

[81] In 2019, she voiced an audio guide in M. Chat exhibit's of world class graffiti artists at Seoul Arts Center.

[85][33] The series is a collection of 35 artworks for each theme of Love, Happiness and Sleep, aiming to serve as guide to those who find it difficult to enjoy art due to lack of professional knowledge.