<p>When environmental officials are deeply embedded in local networks of relationships, strict regulation becomes difficult to sustain. This study investigates whether placing officials from outside these networks in charge of environmental departments can improve governance performance, drawing on panel data from 279 Chinese prefecture-level cities spanning 2007 to 2020. Grounded in principal-agent theory, exchanged officials, who arrive without historically formed ties to local enterprises, face less capture pressure from interest groups and are therefore better positioned to exercise regulatory authority impartially. The findings confirm that inter-regional exchange significantly improves environmental governance performance. The effect is stronger among younger officials with meaningful career advancement at stake, suggesting that relational independence and promotion motivation reinforce each other, and stronger where public environmental participation is higher, as citizen engagement helps exchanged officials identify governance gaps and sustain accountability. Exchanged officials tend to pursue stricter enforcement against polluting enterprises while also navigating budget negotiations more assertively to secure greater fiscal resources for environmental protection. The exchange effect holds even after accounting for observable differences in officials' educational backgrounds and career trajectories, suggesting that the disruption of local interest networks contributes to governance improvement independently of the individual qualities officials bring to the role. These findings speak to a broader challenge facing decentralized governance systems, namely how personnel arrangement, rather than formal regulation alone, can reshape the informal incentive environment within which officials operate.</p>