Nam Yoon-soo began his entertainment career as a model before making his official acting debut in the 2018 MBC Every 1 drama 4 Kinds of House. He then joined the main cast of the 2020 Netflix teen crime series Extracurricular, which earned him a Best New Actor nomination at the 57th Baeksang Arts Awards. That same year, he played a supporting role in the tvN series Birthcare Center. In 2021, he portrayed a young police officer in JTBC’s award-winning murder mystery series Beyond Evil. Later in 2021, he acted alongside Park Eun-bin and Kim Ro-woon in the KBS2 sageuk The King’s Affection, which scored him a Best New Actor nomination at the KBS Drama Awards.

Nam Yoon-soo graduated from Hanlim Arts School and continued his studies at the Digital Seoul Culture Arts University.