Introduction: Adolescent North Korean defectors are vulnerable due to harmful environments during defection, limited access to sex education in North Korea, and exposure to different sexual norms in South Korea. The purpose of this study was to investigate the sexual knowledge, attitudes, and sex education needs of North Korean refugee adolescents. Methods: A cross-sectional, descriptive survey was administered to 102 North Korean refugee adolescents. Results: The correct answer rate for questions on genital anatomy, physiology, masturbation, and contraception was less than 20%. The participants exhibited conservative attitudes toward female contraception, masturbation, and having friends of the opposite sex. A significant positive correlation was found between knowledge and the need for sex education. Discussion: These results highlight the importance of tailored sex education in providing accurate information, improving sexual knowledge, fostering positive attitudes, and enabling healthy behaviors among adolescent North Korean defectors.