BACKGROUND: Limited opportunities to generate income in community-protected areas (CPAs) often lead to the illegal harvesting of wildlife and natural resources, undermining the aim of protected areas. Sustained livestock production can be an alternative income source. OBJECTIVES: To understand the effectiveness and feasibility of livestock production in CPAs. METHODS: We conducted a livestock asset transfer intervention in 25 CPAs across three agroecological zones in Cambodia. We monitored livestock mortality, consumption and sales of livestock over 2 years. Participant observations and structured questionnaires were conducted to elicit information about constraints for livestock production perceived by the participants. A total of 756 households were recruited and 320, 184 and 252 households received chicken, pigs and cattle, respectively. All participants received technical training in livestock production and biosecurity management practices. RESULTS: After the intervention, the number of chickens, pigs and cattle increased on average by 5.9 (range: 0.3-26.3), 0.5 (-1 to 2.7) and 0.12 (0-0.35) per 1 input animal, respectively. The extent of increase was significantly different between zones only for chickens (Kruskal-Wallis test p = 0.004). The number of chickens and pigs sold per household was significantly different among zones. We observed that training was ineffective to alter livestock management practices in some CPAs, which partially explains their suboptimal performance of livestock production. CONCLUSIONS: Understanding contextual factors required for successful livestock production in CPAs is crucial for improving livelihoods and preventing biodiversity loss in Cambodia.