Biodiversity conservation work can be challenging but rewarding, with potential consequences for conservationists’ mental health. Yet, little is known about patterns of mental health among conservationists and its associated workplace protective and risk factors. A better understanding might help improve working conditions, supporting conservationists’ job satisfaction, productivity, and engagement, while reducing costs from staff turnover, absenteeism, and presenteeism. We surveyed 2311 conservation professionals working across 122 countries, asking about experiences of psychological distress, working conditions, and personal characteristics. Over half were from and worked in Europe and North America, and most had university-level education, were in desk-based academic and practitioner roles, and responded in English. Heavy workload, job demands, and organizational instability were linked to higher distress, but job stability and satisfaction with one's contributions to conservation were associated with lower distress. Respondents with low dispositional and conservation-specific optimism, poor physical health, limited social support, women, and early-career professionals were most at risk in our sample. Our results flag important risk factors that employers could consider, though further research is needed among groups under-represented in our sample. We suggest ways employers and others might promote the positives and manage the risks of working in the sector, potentially supporting conservationists’ mental health and abilities to protect nature.