The sustainability of biosphere reserves is arguably linked to socio‐economic factors, yet limited research exists that links socio‐economic factors, sustainable development, and tourism with biosphere reserves. There is thus a need for studies to determine how stakeholders engage in the process of sustainability. Determining stakeholders' perceptions can be useful during several stages of the conservation programme implementation. These perceptions could also indicate how stakeholders would participate in the conservation programme. This research aimed to gauge tourism entrepreneurs' possible behaviour as custodians of the Marico Biosphere Reserve. This was operationalised by determining their perceptions of sustainability. This research applied thematic analysis which identified themes related to the necessity of protecting natural resources, designation uncertainties and how to ensure sustainability. As there is a link between perceptions and behaviour, these results were further contextualised in the protection motivation theory, which raised concerns about tourism entrepreneurs' self‐efficacy and response costs that could hinder the desired protective behaviour in the reserve. Practical implications relate to employing a bottom‐up management approach, creating awareness, sustainable tourism development, and increasing social cohesion, while theoretical implications suggest extending the protection motivation theory with place attachment and social cohesion dimensions. Future research recommendations are suggested.