Seojun is tall with broad shoulders and long legs. As a former idol trainee and a model who must match beauty standards, he is very thin and severely underweight. He has black hair with bangs that sweep across his forehead towards the right side. He has mono eyelids. He is fair-skinned and considered very handsome, often misleading people to assume he is an idol. He is known to have full, supple lips (complimented by both Seyeon, and Jugyeong). Seojun often wears makeup, mainly lip tint.