Drawing on transaction cost economics and social exchange theory, we explore the impact of governance mechanisms on green customer integration and the moderating effects of power and environmental uncertainty. Using data from 206 Chinese manufacturers, we can show that both contractual control and relational norms facilitate green customer integration. Interestingly, the promotional effects of contractual control and relational norms are undermined if manufacturers exert mediated power. Furthermore, the weakened effect of mediated power on the relationship between contractual control and green customer integration is strengthened by demand uncertainty. Conversely, the strengthened impact of non-mediated power on the relational norms–green customer integration relationship is strengthened by demand uncertainty as well as technological uncertainty. This study extends current green supply chain research by revealing that governance mechanisms are antecedent to green customer integration in emerging markets, from the perspective of interfirm relationship management. This study also contributes to transaction cost economics and social exchange theory by revealing how the effectiveness of governance mechanisms on green customer integration varies under different types of power and environmental uncertainty.