Impact investing urges investors to weigh the social and environmental impacts of their investment decisions. However, in practice, it remains unclear whether investors in financial products are driven by ethical motivations, such as environmental considerations, and what factors influence their trust in the non-financial aspects (e.g., green attributes) of these investments. This study investigates the ethical motivations behind investors’ decisions to invest in green bonds using a machine learning-assisted causal inference framework based on data collected on all green and conventional (...) bonds issued worldwide from 2007 to 2022. It also explores the underlying factors contributing to investors’ trust in green bonds by examining four perspectives: the issuer’s environmental performance, the transparency and governance of environmental disclosure related to bonds, and the financing purpose of the bonds. The results indicate that (1) investors are willing to forgo financial gains for environmental causes, with this sacrifice quantified as an 18 basis points (bps) green premium, demonstrating a clear ethical motivation; (2) the credibility of bond information, financing purposes, and issuer’s greenhouse gas emission intensity directly influence investors’ trust in green bonds, while bond information disclosure and the issuer’s environmental (E) scores have only indirect effects; and (3) companies with weaker environmental performance often adopt proactive disclosure or certification policies to bolster investors’ green trust. This study is the first to explore the factors influencing investors’ trust in green bonds and to analyze the overall causal transmission mechanism among these factors using a causal inference framework. (shrink)