Seo Ji-hoon made his acting debut in 2016 with a minor role in the tvN crime thriller Signal. He then appeared in a KBS Drama Special episode titled The Legendary Shuttle, which scored him an Excellence Award nomination at the KBS Drama Awards. Later in 2016, he joined the main cast of the JTBC youth mystery thriller Solomon’s Perjury. In 2018, he played the younger counterpart of Lee Jung-shin’s character in OCN’s time-slip drama Longing Heart. That same year, he acted alongside Moon Chae-won in the tvN fantasy series Mama Fairy and the Woodcutter. In 2019, he starred in the JTBC sageuk Flower Crew: Joseon Marriage Agency. In 2020, he was named Best New Actor at the KBS Drama Awards for his work in Welcome and Men Are Men.
Seo Ji-hoon attended Kyung Hee University.