PurposeCOVID-19 presents a serious and unprecedented challenge around the globe. Street vendors are the most vulnerable group during this pandemic regarding livelihood loss and contagion risk. This research aims to examine the roles of risk communication work in enhancing COVID-19 risk perceptions and adoption of COVID-19 preventive behaviors among street vendors.Design/methodology/approachThe data were collected from the street vendors in urban Vietnam. A binary probit model was used for analyzing the relationships among exposure to risk communication, risk perception and adoption of preventive behaviors.FindingsThe analysis reveals the outreach of risk communication work to the street vendors. A rather large proportion of the respondents perceive high risks associated with COVID-19. All respondents adopt COVID-19 preventive behaviors; however, the proportion of regular adoption is moderate and even very low for most behaviors. Their frequent exposure to risk communication significantly raises their risk perceptions and encourages their regular adoption of preventive behaviors, particularly regarding the measures that are affordable and less detrimental to their livelihood.Originality/valueThis research is among the first attempts to examine exposure to risk communication to the vulnerable group, how they perceive risks and the extent to which they adopt preventive behaviors during a public health crisis. This research draws some implications for risk communication and social welfare policies to obtain sustainable development goals.