Kim Yoo Jung

Biography

In Dear X, Baek Ah-jin can look perfectly composed while calculating how to use the person standing opposite her. Kim Yoo Jung plays that unsettling contradiction with a restraint that feels worlds away from the openhearted heroines many K-drama viewers know her for. It isn’t a sudden change of direction. Her career has spent years moving between innocence, mischief, vulnerability and, increasingly, characters who keep their intentions hidden.

Born on September 22, 1999, Kim Yoo Jung (김유정) began working as a child, with a 2004 commercial and an early screen appearance in Demilitarized Zone. She played the younger Dong Yi in the 2010 historical series and the young Heo Yeon-woo in The Moon Embracing the Sun (2012). In those roles, her job was more than introducing an adult character: the early relationships and losses had to feel important before the story moved forward in time.

Her work was never limited to sweet period-drama introductions. In the film Thread of Lies (2014), she took part in a story about bullying and its consequences. Angry Mom (2015) then gave her Oh Ah-ran, a teenager caught inside the school violence and corruption her mother tries to confront. These projects placed difficult social material beside her later romantic roles.

Love in the Moonlight (also called Moonlight Drawn by Clouds) became a decisive leading-role breakthrough in 2016. As Hong Ra-on, a young woman disguised as a male palace eunuch, she had to balance quick comic timing with the fear of being discovered. Her scenes opposite Park Bo-gum’s Crown Prince Lee Yeong depend on that tension: Ra-on can speak freely in one moment and must remember the danger of her disguise in the next. Kim received the female Excellence Award for a mid-length drama at the 2016 KBS Drama Awards for the role.

She subsequently moved through very different kinds of romance. Backstreet Rookie (2020) made her Jung Saet-byul, the bold convenience-store employee opposite Ji Chang-wook; the character’s physical confidence and blunt humor helped distinguish the workplace comedy from her palace roles. In Lovers of the Red Sky (2021), she returned to historical fantasy as Hong Cheon-gi, a gifted painter whose story connects art, fate and romance. One performance runs on lively confrontation; the other has to make an imagined world feel emotionally believable.

The Netflix film 20th Century Girl (2022) offered another shift in scale. As Na Bo-ra, she plays a teenager who agrees to observe a boy for her best friend and discovers that her own feelings won’t stay neatly outside the arrangement. The story gives ordinary gestures and misunderstandings weight without needing supernatural stakes. It also shows how well Kim can carry a film built around friendship, memory and first love rather than a long television romance.

Then came My Demon (2023–24). Her Do Do-hee, a guarded heiress who enters an uneasy arrangement with Song Kang’s demon Jeong Gu-won, isn’t simply a romantic lead waiting to be rescued. The relationship works because both characters begin by protecting their own interests. Kim won the 2023 SBS Drama Awards’ Top Excellence Award for a romance or romantic-comedy miniseries, while she and Song Kang received the Best Couple award.

Dear X (2025) pushed that guarded quality somewhere far darker. As Baek Ah-jin, an actress who manipulates others while climbing to fame, Kim has to communicate calculation even when the character refuses to reveal much emotion. In interviews about the series, she discussed the difficulty of suppressing feelings rather than displaying them. That makes the part especially interesting beside Hong Ra-on or Na Bo-ra: the familiar expressiveness is still there, but deliberately held back.

In October 2026, she returned to a historical setting with 100 Days of Deception, which premiered on October 10. She plays Lee Ga-kyung, a skilled pickpocket drawn into undercover work for the independence movement in Japanese-occupied Gyeongseong. It is another story where the character survives by performing a false identity, but here the deception belongs to espionage rather than palace romance. Across these roles, Kim Yoo Jung’s defining skill isn’t one particular genre. It’s making the difference between what a character feels and what she can safely show worth watching.