<p>How can stakeholders distinguish genuine firm commitment from opportunistic greenwashing? This study investigates the ethical dimensions of this challenge, arguing that the strategic value of third-party certification depends on its temporal design, which distinguishes credible signals of commitment from ethically problematic symbolic acts of decoupling. Using a matched sample of Chinese green bonds, we show static, pre-issuance certification tends to be associated with initial financing benefits that on average reverse into secondary-market penalties consistent with perceived decoupling and weak ethical signaling. This pattern appears to be amplified by adverse selection, creating an ethical hazard for the market. In contrast, post-issuance certification, representing a stronger ethical commitment, tends to create more sustained value. These effects are moderated by certifier reputation, external scrutiny, and market maturity, which function as mechanisms of accountability that bolster market integrity. We contribute to signaling and institutional theories by showing that the temporal design of certification determines its ethical accountability, distinguishing credible commitment from symbolic compliance in sustainable capital markets.</p>