ABSTRACT This study aimed to determine the underlying factors influencing street food vendors’ implementation of food safety behaviours related to food handling. A questionnaire based on the Theory of Planned Behaviour was applied to 303 street food vendors in Southern Brazil. Open-ended questions identified that consequences related to consumers were important factors influencing street food vendors’ food safety behaviour. Also, water supply and lack of water were identified, respectively, as possible facilitators and barriers to carry out food safety behaviours such as handwashing and cleaning the shelf used to prepare food. Optimistic bias was identified and the majority of street food vendors gave positive results related to perceived behavioural control, subjective norm, attitude and behavioural intention. Improvements are needed in government regulation, infrastructure and food safety training for this sector, with measures that reflect and are adapted to the street food environment.