Ji Il-joo debuted as an actor in the 2008 KBS2 series Women in the Sun and has since become active in both the big and small screens. In 2012, he joined the hit MBC medical series Golden Time. He also appeared in the 2013 tvN period drama Basketball. In 2014, he played a supporting role in the KBS2 action-thriller Healer. In 2016, he became part of JTBC’s Age of Youth and the MBC sports campus drama Weightlifting Fairy Kim Bok-ju. In 2019, he made his debut as director and screenwriter in the indie film Huris, in which he also starred. That same year, he was cast as lead in the film My Bossy Girl, opposite Lee Elijah. In 2020, he portrayed one of the main characters in the movie Dragon Inn Part 1: The City of Sadness. He then returned for its 2021 sequel titled Dragon Inn Part 2: The Night of the Gods.