Social-ecological systems are complex and involve uncertainties emerging from interactions between biophysical and social system components. In the face of growing complexity and uncertainty, stakeholder engagement with the future is important to proactively manoeuvre toward desirable outcomes. Focusing on the interrelated challenges of food security and biodiversity conservation, we conducted a participatory scenario planning exercise in a rural landscape in southwestern Ethiopia. We involved 35 stakeholder organizations in multiple workshops to construct causal loop diagrams, elicit critical uncertainties, and draft scenario narratives. Jointly, we developed four plausible future scenarios for the studied landscape: (1) gain over grain: local cash crops; (2) mining green gold: coffee investors; (3) coffee and conservation: a biosphere reserve; and (4) food first: intensive farming and forest protection. These scenarios differ with respect to their main social-economic dynamics as well as their food security and biodiversity outcomes. Importantly, three of the four scenarios, i.e., all except "coffee and conservation: a biosphere reserve," focused on increasing efficiency in agricultural production through intensification, specialization, and market integration. In contrast, "coffee and conservation: a biosphere reserve" was driven by agroecological production methods that support diversified livelihoods, a multifunctional landscape, maintenance of natural capital, a governance system that supports local people, and social-ecological resilience. Similar agroecological trajectories have been advocated as desirable for sustainable development in numerous other smallholder farming systems worldwide. Given fewer trade-offs and better equity outcomes, it appears that an agroecological development pathway stands a good chance of generating synergies between food security and biodiversity conservation. Pathways prioritizing agricultural efficiency, in contrast, are more likely to degrade natural capital and cause social inequity.