This paper analyses the relationship between firms' investment in green technologies and competitive performance. We take advantage of new data on the adoption of different green technologies (circular economy, technical advancements, energy savings, and efficiency gains) from a large representative sample of Italian firms. We find the following results. First, overall green investment increases the sales per employee and average wages. Second, we show a significant heterogeneity in the estimated effect across different green technologies. These results are robust to different checks, accounting for a large set of observed characteristics, time-invariant unobserved heterogeneity and endogeneity issues. In sum, our results support the hypothesis that the ongoing ecological transformation of productive processes may favor firms' competitiveness, but substantial heterogeneity still matters. The policy implications are then discussed.