Background Worldwide prevalence of physical inactivity is high. Walking for transportation is a domain of physical activity that contributes to increase it in daily life. Built urban environment attributes have been correlated with its practice, particularly in high-income countries. However, literature is controversial and scarce in low and middle-income countries. Aims The study aimed to evaluate the relationship between built urban environment and walking for transportation among adults in Cali, Colombia. Methods It was a secondary analysis of baseline information based on a multilevel cohort study. In 729 subjects aged between 18-44 years of Cali, were applied surveys about demographic variables and physical activity through long IPAQ questionnaire. Built urban environment variables of the 71 micro-territories generated were measured with GIS, in 3 buffers (500, 750m2, and total residential area). Crude and adjusted OR's were obtained with logistic hierarchical regression for 3 cutoffs of time walking for transportation (?30, ?60 and ?150 minutes per week). The study was approved by the ethics committee at Universidad del Valle. Results For each cutoff, the prevalence was 59%, 46% and 18%, respectively. About 40% were men and half were 30 years (IQR 23-36). After adjusting for individual and contextual variables, walking ?60min was associated with excellent to good perception of safety in neighborhood (OR=1.6, 95%CI 1.1-2.2). For walking ?30min, owing motorcycle or car reduced the probability in 40% (95%CI 0.4-0.9), but the highest tertile of trees/hectare index increased it (OR=2.0, 95%CI 1.2-3.4). Marginal negative relationships were found with park area index and points of traffic lesions. Conclusions This study highlights some environment features related to walking for transportation, in the context of a middle-income country, where physical inactivity is a public health problem. More research is necessary to better understand and to intervene physical and social urban environmental determinants of physical activity.