Lee Soo-kyung debuted as an actress in the 2012 film In the Summer. In 2015, she joined the main cast of tvN’s Ho-gu’s Love and also made a cameo appearance in Answer Me 1988. That same year, she was cast in the movie Coin Locker Girl. In 2017, she played the titular character in the drama film Yongsoon, which scored her numerous Best New Actress nominations. She then starred in the 2017 crime-drama film Heart Blackened, which won her Best Supporting Actress at the 54th Baeksang Arts Awards. In 2018, she was nominated for Best New Actress at the SBS Drama Awards for Fox Bride Star. In 2021, she became part of the JTBC legal series Law School. Also in 2021, she worked with Park Jung-min, Yoon-ah, and Lee Sung-min in the romantic drama film Miracle: Letters to the President, which gave her another Baeksang Best Supporting Actress trophy.