Natural resources remain central to economic growth and social welfare, yet managing them sustainably continues to be a major challenge for countries striving to balance development with environmental protection. This study examines how mineral rents, mineral depletion, total natural resource rents, and public–private partnership (PPP) investment in water and sanitation interact and influence biodiversity conservation in China between 1980 and 2022. The results show that PPP investment in water and sanitation plays a positive role in biodiversity protection by improving water quality, easing environmental pressure, and promoting better management of ecological resources. In contrast, mineral rents and overall natural resource rents are negatively associated with biodiversity, highlighting the ecological risks that arise when resource exploitation intensifies. Mineral depletion also affects biodiversity loss, although its interaction with PPP investment suggests that coordinated efforts between public and private sectors can help soften some of the environmental costs linked to extraction. Overall, the findings point to the need for China to build a more integrated policy framework that links mineral rent management, depletion control, and biodiversity conservation. Such a framework should include mechanisms for evaluating the environmental and economic trade-offs of resource extraction and for promoting strategies that protect biodiversity while supporting long-term sustainable development.