This paper investigates the impact of green, digital, and twin transition investments on firm performance in Italy during the 2014-2020 programming period. Drawing on detailed project-level data from the OpenCoesione platform on ERDF-funded initiatives, we classify investments according to their thematic focus and apply a staggered Difference-in-Differences approach to estimate their effects on value added, employment, and labour productivity. Our results show that firms supported through twin transition projects, those combining green and digital components, achieve the most substantial and sustained gains in value added and productivity. These integrated interventions appear particularly effective in enhancing firm performance and capacity utilisation, with employment effects emerging more gradually. Purely green and digital projects also yield positive outcomes, though with more moderate and variable effects. We further document significant heterogeneity across regions and sectors, with stronger impacts observed among firms located in Northern and Southern Italy and in knowledge-intensive sectors. Our findings highlight the importance of strategic investment design: transition-oriented and multi-dimensional projects consistently outperform single-focus initiatives. These results suggest that EU cohesion policy plays a pivotal role in supporting structural transformation, particularly when funding is targeted to integrated projects that align with broader environmental and digital policy goals.