Jo made his entertainment debut in 1998 as a model for clothing brand Ziozia. In 2000, he began his acting career by starring in the teen drama School 3 and in the second season of the sitcom Nonstop.

In 2001, Jo first drew notice in a supporting role in the television drama Piano, co-starring Go Soo as his stepbrother. He was cast in his first drama leading role in 2002, as an illiterate actor in Shoot for the Stars opposite Jeon Do-yeon.

Meanwhile, on the big screen, Jo starred in three romance-themed films in 2003, notably Kwak Jae-yong’s The Classic, with Son Ye-jin and Jo Seung-woo.

In 2004, Jo returned to television in What Happened in Bali, alongside Ha Ji-won and So Ji-sub. Aside from its high ratings, Jo won the Best Actor awards at both the Baeksang Arts Awards and SBS Drama Awards. In 2005, he starred opposite Go Hyun-jung in her comeback drama Spring Day, a remake of the Japanese drama Hoshi no Kinka (“Heaven’s Coins”).