The recent decades have witnessed the rise of digital media; as an essential informal way of environmental education, the internet has become an important source where public acquire environmental knowledge. The current study investigates the heterogeneous treatment effects of internet use on environmental knowledge across members of the Chinese population. Based on a nationwide survey in China, the propensity score approach, a series of statistical techniques that are often used in the counterfactual framework to understand the causal relationship between an intervention and an outcome, is employed to adjust for population heterogeneity and to estimate heterogeneous treatment effects. The findings reveal highly significant positive associations between internet access/use and environmental knowledge. More importantly, this study shows that individuals who are least likely to access the internet benefit most from the knowledge returns to internet access and use, indicating a positive outlook for the potential of the digital media to narrow the environmental knowledge gap.