To extend the Porter hypothesis, this study defines environmental regulation in terms of two dimensions (i.e., industry and region) and explores their roles in R&D investment and innovation performance. We focus on how environmental regulation affects firms' innovation performance directly and whether it promotes or impairs the relationship between R&D investment and innovation performance. Based on a quantitative analysis of panel data from Chinese technology-intensive manufacturers, the results show that, first, R&D investment has a direct positive effect on firms' innovation performance. Second, industrial regulation negatively affects innovation performance, while regional regulation facilitates innovation performance. Third, regional regulation plays a negative moderating role between R&D investment and innovation performance; however, the industrial regulation's moderating effect is positive. This paper provides guidance for corporate innovation under mandatory environmental regulations. Future research may consider introducing voluntary environmental regulations into the theoretical framework.