Although she had wanted to be in a musical for a long time, she rejected casting offers because she felt unprepared.
In January 2014, her wish was fulfilled as she accepted her first musical acting role.
A member of a top K-pop group, "Girl's Generation (aka SNSD)" and an actress, Seohyun made a huge image change with SNSD's new song, Holiday Night.
On the 31st, SNSD released a new teaser image and video clips for Holiday Night and Seohyun was the 6th member whose image was released.
Seohyun played the lead role, Yeon-woo, the daughter of a noble family who has a love relationship with both the King and his brother.
The musical had previously earned nine nominations at the 2013 Korea Musical Awards.
She played a character named Sophie, a 20-year-old bride-to-be, who hopes to find out who her biological father is on her wedding day.
Kim Geum-yeong from CNB Journal commented on Seohyun's improvement from her prior musical performances, praising her "natural acting" and "daring side" while Park Jeong-hwan from News1 claimed Seohyun's performance made the musical "all the more entertaining".
She voiced the character Edith, who is known for her rebellious attitude.
In April 2012, a Girls' Generation subgroup named TTS was formed with Seohyun and fellow members Taeyeon and Tiffany.
She co-wrote the songs "Baby Maybe" and "XYZ" (I Got a Boy, 2013) and was credited as the sole lyricist for "Only U" (Holler, 2014) and "Dear Santa" (Dear Santa, 2015).
In 2013, Seohyun's acting career began when she was cast in a small role in SBS's drama Passionate Love.
Her parents did not encourage her to become a celebrity, but Seohyun credited them as the ones who helped her choose her career path by letting her experience different things.