Jo Jung-seok made his professional acting debut in the musical The Nutcracker in 2004. In 2008, he won Best New Actor at the 14th Korea Musical Awards for his work in Organ in My Heart, which was adapted from a 1999 Korean movie. In 2009 and 2010, he collected two Best Supporting Actor trophies for his performance in the Korean production of Spring Awakening.
In 2011, Jo Jung-seok was cast in his first television role in the MBN musical drama What’s Up. His breakout role came the following year in his debut movie Introduction to Architecture. His portrayal of the young hero’s best friend won him Best New Actor at the 33rd Blue Dragon Film Awards. He also scored Best Supporting Actor nominations at the 49th Grand Bell Awards and the 21st Buil Film Awards for the movie. Also in 2012, he was cast in the MBC drama The King 2 Hearts, in which he was nominated for Best New Actor for TV at the 49th Baeksang Arts Awards. In 2013, he landed his first leading role in the KBS2 drama You’re the Best, Lee Soon-shin, which won him an Excellence Award at the KBS Drama Awards. That same year, he won Best Supporting Actor trophies at the 50th Grand Bell Awards and the 33rd Korean Association of Film Critics Awards for the movie The Face Reader.
Aside from acting, Jo Jung-seok also lent his voice to the official soundtracks of some of his dramas. In 2020, the song Aloha that he sang for the tvN series Hospital Playlist took home numerous Best OST awards.
Jo Jung-seok was granted exemption from military service because his mother became fully dependent on him after his father passed away. He married singer Gummy on October 8, 2018. Their first daughter was born on August 6, 2020.