Katsuki is a young man of average height, with a slim, muscular build, and a fair skin tone. He has short, spiky, sandy blond hair with choppy bangs that hang over his eyebrows. His eyes are sharp and bright red in color.
At school, he wears the standard U.A. uniform without the customary red tie. Underneath his blazer, he wears a white collared shirt with the top few buttons undone. His pants are worn loosely, causing them to sag at his ankles, despite him wearing a belt with them.