She is best known for her roles in Encounter (2018), VIP (2019), Hospital Playlist (2020), Inspector Koo (2021), Behind Every Star (2022), and Brain Works (2023).

That same year, she made her first television appearance in the mini-series Your Honor, where Kwak plays Song Ji-yeon, a victim of sexual assault.

[11] She later got her first supporting role as Song Hye-kyo's best friend and personal secretary in the television series Encounter.

[11] In 2020, Kwak starred in the medical drama Hospital Playlist, as Lee Ik-sun, younger sister of Lee Ik-jun (Jo Jung-suk) and love interest of Kim Jun-wan (Jung Kyung-ho).

[14] Kwak Seon-young married her non-celebrity husband in 2015 and gave birth to a son the following year.