Sponsorship in pro-environmental social marketing campaigns has received limited academic attention within a higher education (HEI) context. This study examines how multi-level variables, i.e. individual (general environmental attitudes), organisational (scepticism toward the HEI's environmental corporate social responsibility (CSR) initiatives; perceived HEI behaviour) and campaign-related (attitudes toward the advertisement; attitudes toward the corporate sponsor) factors, influence university students' environmental intentions in response to a corporate-sponsored environmental initiative; using mixed methods (231 surveys and 40 interviews). Questionnaires revealed that scepticism toward the HEI's CSR initiatives led to less positive perceptions of the HEI's environmental behaviour, which decreased positive attitudes toward the advertisement and environmental intentions. Interviews revealed that the corporate sponsor seemed to motivate environmental behavioural intentions due to product discounts related to the sponsorship. Thus, a corporate sponsor may have confounding effects on pro-environmental behaviour campaigns. This has implications for the use of sponsorship in environmental social marketing campaigns.