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 protective and risk factors. A better understanding may 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, personal characteristics, and workplace conditions. 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. Moderate or severe distress was reported by 27.8% (Kessler Psychological Distress Scale scores over 24). 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. Heavy workload, job demands, and organisational instability were linked to higher distress, but job stability and satisfaction with one’s contributions to conservation were associated with lower distress. 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.