Green Technology innovation intends to enable the advancement of technologies toward the goals of human health, natural resource sustainability and social equity. Green technology innovation has become an important driving force for the sustainable growth of the global economy. In this study, building upon the theories on informal institutions, we empirically investigate the effects of social trust on green technology innovation. Using a sample of companies listed in A-share markets in China from 2012 to 2017, we find that social trust has a significant positive impact on the performance of green technology innovation. We employ an instrumental variable approach through two-stage-least square estimator, and report consistent results. Further heterogeneity analysis finds that with higher levels of policy uncertainty and lower levels of intellectual property rights protection, the effect of social trust on firms’ green technology innovation is more significant. Further, the effect of social trust on firms’ green technology of non-SOEs innovation is larger than SOEs. In addition, the positive effect of social trust on green technology innovation in firms is an effective supplement for formal systems to promote green technology innovation in said firms, which provides a new theoretical reference for promoting firms’ green technology innovation and achieving high-quality development.