The world health organization has described obesity as one of today’s most neglected public health problems, affecting developed and developing countries in the world. Indians now report more and more frequently with overweight, obesity, and their consequences. This study was aimed to determine the prevalence and associate factors of obesity among adults in Theni district, Tamil Nadu State, India. Study design was cross-sectional and institutional based study. Data was collected in government hospitals and primary health center (PHC’s) in Theni District. 680 samples were collected with convenient sampling technique. Appropriate descriptive and analytical (frequency, standard deviation, binary logistic regression) were used to determine the prevalence and statistical significant association between the variables with SPSS version 20. The overall prevalence rate of overweight/obese among adults was 52.4%, more over females overweight/obese was 22.8% -34.8% and in males overweight/obese was 23.4-22%. Prevalence of obesity/overweight (BMI) age, gender, marital status, occupation, income meat/egg consumption and snack consumption were statistically significant association with Obesity (BMI) (P< P<0.05). Abdominal obesity increased in female 78.5% than male 49.6%. In Bivariate analysis result shows age between 18-34 were 1.55 times more likely to be obese than those who are greater than or equal to 50 years [ (COR=1.55(1.03,2.34)], Multivariate logistic analysis result revels that the likely hood be being obese among respondents of married living with partners were 1.76 times higher than those who were separated and diverted [AOR= 1.76(1.12, 2.78)], and Prevalence of male respondents was 0.64 times lower than female AOR=0.64 (0.42, 0.97). The prevalence of obesity was also 0.44 times lower among Hindus than other religions [AOR=0.44(0.21-094)]. An increasing prevalence of obesity was seen epically in south India. Hence, there is an urgent need to address the trouble and efforts should be made to prevent the epidemic of obesity and its allied health disasters in South India.