This study aimed to identify the level of stress in teenagers from multicultural families in Korea and examine the factors influencing this stress. This cross-sectional study utilized the 15th (2019) Korea Youth Risk Bsehavior Web-based Survey. Of the 57,303 survey participants, 749 reported that their father, mother, or both parents were born outside of Korea. These 749 multicultural individuals were selected as study participants. We examined general characteristics (sex, grade, parental education level, academic performance level, foreign nationality, residence type, economic status, exposure to violence, and frequency of physical activity), health risk behaviors (sexual activity, drug use, and drinking), and mental health factors (sleep, depression, and presence of suicidal thoughts) to determine whether these factors may contribute to multicultural adolescent stress. Multicultural adolescents who reported insufficient sleep, depression, or suicidal thoughts were more likely to experience stress than those who did not report these factors. Moreover, participants with insufficient sleep were 3.73 times more likely to feel stress than those with good sleep. Among general characteristics, health risk behaviors, and mental health factors, mental health factors were observed to significantly predict an increase in multicultural adolescents’ stress levels. Considering the increase in the number of multicultural adolescents in Korea, it is important to address the difficulties they experience to provide appropriate interventional programs. Such programs should include techniques to help with the management of stress.