This study aimed to analyze the association between physical activity, subjective health perception, and obesity among adolescents from multicultural families in Korea. Using raw data from the 19th (2023) Korean Youth Health Behavior Survey, a total of 1,337 adolescents from multicultural backgrounds were selected. For analysis, SPSS 25.0 was used to adopt complex sample analysis methods, including weighting, stratification, and clustering. The main statistical methods used were the chi-square test for associations and logistic regression to calculate odds ratios (ORs). Results showed a significant positive association between all types of physical activity (≥ 60 minutes of exercise, high-intensity exercise, and strength training) and subjective health perception (p < 0.05). Strength training was also significantly associated with a more positive subjective body image (p < 0.05). However, no direct statistically significant relationship was found between physical activity categories and the prevalence of obesity. Logistic regression analysis results showed that a more positive subjective health perception significantly lowered the risk of obesity, but subjective body image perception did not have a significant effect. These results highlight the importance of physical activity in the subjective well-being of multicultural youth, while also demonstrating the complex and multifactorial nature of obesity in this population.