Hong Jong-hyun started out as a model before debuting as an actor in 2008 with appearances in the films Lovers and A Frozen Flower. In 2014, he was named New Star of the Year at the MBC Entertainment Awards for his participation in the reality-variety show We Got Married, where he was paired with Girl’s Day’s Yura. That same year, he was nominated for Best New Actor at the MBC Drama Awards for his work in Mama. In 2016, he played a supporting role in the SBS sageuk Moon Lovers: Scarlet Heart Ryeo, which scored him an Excellence Award nomination at the SBS Drama Awards. In 2017, he acted alongside Im Shi-wan and Yoon-ah in MBC’s The King Loves, which earned him an Excellence Award nomination at the MBC Drama Awards. In 2019, he received another Excellence Award nomination at the KBS Drama Awards for his performance in Mother of Mine.

Hong Jong-hyun enlisted for his mandatory military service in December 2019 and was discharged in October 2021.