[3] In 2009, he appeared in My Too Perfect Sons, playing the timid, youngest brother who ends up raising his best friend's daughter at just 20 years old.

[14] On his first antagonist role in the melodrama, Five Fingers (2012), Ji played a pianist who envies his older brother's natural gift for music.

[15][16] Ji returned to musical theater in 2013 with The Days, playing a presidential bodyguard who went missing 20 years ago along with a mysterious female companion.

[17] Ji's breakthrough came through his role as Toghon Temür (also known as Ta Hwan), the 16th emperor of the Yuan Dynasty, in the historical drama Empress Ki.

[25][26] In 2016, Ji starred as the male lead in tvN's action-thriller The K2, a bodyguard who is betrayed by his fellow countrymen and falls in love with a girl with PTSD and apparent sociophobia.

[29] In 2017, Ji starred in the action film, Fabricated City, playing the role of a jobless game addict who is framed for murder.

[31] Following his discharge from military in 2019, Ji was cast in the romantic comedy series Melting Me Softly, where he played the role of a television producer who finds himself waking up 20 years into the future following an unsuccessful human-freezing project.

In 2021, he starred in the Kim Chang-ju's thriller film Hard Hit, playing a mysterious caller who blackmails the protagonist and his family with a bomb planted inside the car they are driving.

[34] In 2022, Ji appeared in the Netflix series The Sound of Magic, based on a webtoon of the same name, in the role of mysterious magician Lee Eul.

[42] Ji was assigned to the Army's 5th Artillery Brigade at Cheorwon, Gangwon Province, to complete the remainder of his military service.