Protected areas (PAs) are a key strategy for protecting biological resources, but they vary considerably in their effectiveness, and are frequently reported as having negative impacts on local people. This has contributed to a divisive and unresolved debate concerning the compatibility of environmental and socioeconomic development goals. Elucidating the relationship between positive and negative social impacts and conservation outcomes of PAs is key for the development of more effective and socially just conservation. Here, we conduct a global analysis of how PAs affect the wellbeing of local people, the factors associated with these impacts, and crucially the relationship between PAs’ conservation and socioeconomic outcomes. Our results show that PAs reporting positive socioeconomic outcomes are more likely to report positive conservation outcomes. We find positive conservation and socioeconomic outcomes are more likely to occur when PAs adopt co-management regimes, empower local people, reduce economic inequalities and maintain cultural and livelihood benefits. While the strictest regimes of PA management attempt to exclude anthropogenic influences to achieve biological conservation objectives, our study provides evidence that PAs that explicitly integrate local people as stakeholders tend to be more effective at achieving joint biological conservation and socioeconomic development outcomes. Strict protection may be needed in some circumstances, yet our results demonstrate that conservation and development objectives can be synergistic and highlight management strategies that increase the probability of achieving win-win scenarios that maximize conservation performance and development outcomes of PAs.