Purpose: Unhealthy (vice) on-the-go (OTG) dietary practices result in potentially serious health consequences. However, research on encouraging healthy eating intentions for OTG consumption is scarce. This study aims to fill this gap by investigating the role of message framing and source expertise in encouraging the healthy eating intention for OTG consumption. Design/methodology/approach: Two scenario-based experiments were conducted. Study 1 collected data from 136 Australian OTG consumers to examine the effectiveness of message framing (gain vs loss) in encouraging healthy OTG consumption. Study 2 collected data from 178 Australian OTG consumers to examine the interaction effects of message framing and source credibility on encouraging healthy OTG consumption. Findings: Gain-framed messages were more effective than loss-framed messages in encouraging healthy eating for OTG consumption. This difference would be significant only if the gain-framed messages were from a high expert source rather than from a low expert source. Research limitations/implications: The study is a cross-sectional survey of Australian OTG consumers. Replicating this study in other countries may generalise the study’s findings. Practical implications: Practically, this study provides insights to marketers and other relevant stakeholders to design effective advertising messages to encourage healthy eating for OTG consumption. Originality/value: This is the pioneering study investigating the impact of message framing and source credibility in encouraging healthy eating for OTG consumption.