This study aimed to quantitatively determine the sociocultural adaptation profiles of ethnic minority senior high school students in mainland China. A large-scale questionnaire survey of 1873 Grade 12 students from 31 interior ethnic boarding schools throughout China was conducted. Through exploratory and confirmatory factor analyses, the underlying structure of the sociocultural adaptation questionnaire was uncovered as consisting of three domains and six factors: General adaptation (daily life and school management), academic adaption (learning strategies and learning self-efficacy), and interaction adaptation (interethnic contact and cultural identity). By performing latent class analysis, four distinct sociocultural adaptation profiles of students were distinguished: The well-adapted group (28.0%), the general adaptation group (31.0%), the interaction adaptation group (24.4%), and the maladaptation group (16.6%). The results of chi-squared and variance analyses showed that the sociocultural adaptation profiles of ethnic minority senior high school students were significantly related to sociodemographic variables, such as ethnicity, class organization, hometown location, and family socioeconomic status. These profiles can be used to evaluate changes in ethnic minority students’ sociocultural adaptation and will contribute to the perfection of the ethnic minority boarding school system and the ultimate realization of inclusive and equitable quality education in China.