At different lifecycle stages, enterprises possess differentiated resource endowments and innovation needs, leading to variations in the effect of carbon emission trading policies on their green innovation. This study analyzes the impact of China’s carbon emission trading policy on green innovation, using A-share listed firms in Shanghai and Shenzhen between 2010 and 2022 as samples, from the perspective of the enterprise lifecycle. The results validate the Porter hypothesis, showing that the policy stimulates green innovation, especially in the growth and maturity stages of enterprises. However, the extent of this impact varies across enterprise scale heterogeneity, heterogeneity in the proportion of independent directors, heterogeneity in the level of green innovation and regional heterogeneity. The carbon emission trading policies can mitigate financing constraints and improve capital investment to foster green innovation, especially for mature enterprises. The findings not only enhance the theoretical investigation of flexible market-oriented environmental regulatory mechanisms but also provide valuable insights for advancing the growth of China’s low-carbon economy.