Lee Won-jong made his acting debut in 1999 with the film Nowhere to Hide. He has since become one of the most visible actors in the local acting scene. In 2001, he appeared in the hit gangster comedy film Hi! Dharma! The following year, he joined the main cast of high-rating SBS drama Rustic Period, which won him Best Supporting Actor at the SBS Drama Awards. In 2003, he landed a role in director Lee Jun-ik’s war comedy movie Once Upon a Time in a Battlefield. In 2007, he became part of the SBS series War of Money, which gave him another Best Supporting Actor trophy at the SBS Drama Awards. In 2008, he was cast in the KBS sageuk King Sejong the Great, which scored him an Excellence Award at the KBS Drama Awards. In 2013, he played a supporting character in the popular MBC sageuk Empress Ki. In 2015, he starred in the tvN crime thriller Hidden Identity. In 2021, he was announced to play the role of Moscow in the Netflix series Money Heist: Korea – Joint Economic Area, which was based on the Spanish drama La Casa de Papel.

Lee Won-jong attended Kyonggi University.