Lee Hyun-woo began acting as a child. Some of his early works are the big-budget MBC fantasy epic series Legend and the SBS drama Lobbyist, which both aired in 2007. In 2008, he played the young counterpart of Kim Sang-kyung’s character in the KBS sageuk King Sejong the Great, which won him Best Young Actor at the KBS Drama Awards. In 2012, he was cast as the teenage version of Uhm Tae-woong’s character in the KBS2 series Equator Man, which earned him a Best New Actor nomination at the KBS Drama Awards. That same year, he took home the New Star Award at the SBS Drama Awards for the youth rom-com To the Beautiful You. He then starred with Kim Soo-hyun and Park Ki-woong in the 2013 action comedy-drama film Secretly, Greatly, which gave him numerous Best New Actor nominations. In 2015, he appeared in the naval thriller film Battle of Yeonpyeong, which scored him the Best Supporting Actor trophy at the 49th WorldFest-Houston International Film Festival. In 2016, he headlined the KBS2 action-romance series Moorim School. In 2017, he was paired with Red Velvet’s Joy in the tvN romantic comedy The Liar and His Lover, which was based on the popular Japanese manga Kanojo wa Uso o Aishisugiteru.

Aside from acting, Lee Hyun-woo also contributed his voice to the official soundtracks of some of his projects. He also released several singles such as Your Face with Geeks’ Louie in 2016 and Twenty-six in 2018.

Lee Hyun-woo enlisted for his mandatory military service in February 2018 and was discharged in October 2019.