The divergence in cardiovascular disease risk among Asian countries may be related to differences in economics, lifestyles, and cultural backgrounds. We examined the differential association of overweight and hypertension between the high- and middle-income Asian countries, namely Japan and Thailand and extended to compare other cardiovascular risk factors between these two countries, using the data sets from the annual health examinations conducted in 127,152 Japanese (mean age, 41.5 ± 11.1 years; mean body mass index [BMI], 22.4 ± 3.4 kg/m2) and 4243 Thai (mean age, 47.9 ± 10.7 years: mean BMI, 24.0 ± 3.7 kg/m2) aged over 18 years with no history of hypertension treatment. Hypertension was diagnosed as office SBP ≥ 130 mmHg and/or office DBP ≥ 80 mmHg. Overweight was defined as BMI ≥ 25 kg/m2. The analysis using the direct standardization method showed a lower prevalence of hypertension in the Japanese than in the Thai population (31.8% vs. 57.3%, P < 0.001). The Japanese population had higher estimated glomerular filtration rate and lower cholesterol level and BMI than in the Thai population (all P < 0.001). The association between overweight and hypertension was observed in both populations regardless of age and sex (all P < 0.05). In the analysis stratified by age and sex, the association between overweight and the presence of hypertension was more prominent in the Japanese population aged <50 years in both sexes compared with the Thai population (all P for interaction < 0.001). These results confirmed the differential impact of overweight on hypertension between the high- and middle-income countries even in the similar regions of Asia.