To assess the prevalence and correlates of low physical activity among Iranian population aged 15‐64 years. We used the data collected in National Surveillance of Risk Factors of Non‐Communicable Diseases in Iran, 2011. Physical activity was categorized in 3 levels of low, moderate, and high based on a Persian version of Global Physical Activity Questionnaire. The multistage cluster sampling design was accounted for using complex survey analysis method. The sample included 10016 individuals; 41.7% (n = 4178) were men and 58.3% (n = 5837) were women. The mean (SD) age of participants was 38.8 (14.9) years also, and 69.8% (n = 6991) of the participants were from urban areas. The prevalence of low physical activity in the whole population was estimated to be 44.8% (95% CI: 41.7, 48.1). The odds of lower physical activity in the women were 3 times greater than men (OR = 3.14; 95% CI: 2.64, 3.57); in the wealthiest people was 25% lower than the poorest people (OR = 0.75; 95% CI: 0.60, 0.94). The odds of lower physical activity in the age groups 55‐64 years were 44% greater than the youngest age groups 15‐24 years (OR = 1.44; 95% CI: 1.23, 1.68). The odds of lower physical activity in the obese participants were 18% greater than normal‐weight people (OR = 1.18; 95% CI: 1.01, 1.38).). The odds of lower physical activity in diabetic patients were 30% greater than healthy people (OR: 1.30; 95% CI: 1.07, 1.57). The prevalence of low physical activity in Iran, 2011 was high. The correlates of low physical activity in Iran are different to those of Western populations. The main associated factors with low physical activity were female gender, urban area, low socioeconomic status, obesity, diabetes, and older age. Public health policies should target the groups at highest risk of low physical activity.