Tackling human-caused global warming and ecological degradation requires rapid transformative change in production and consumption patterns. In this regard, eco-innovations represent a cornerstone for reducing environmental burdens and strengthening sustainability. However, recent global efforts to scale up eco-innovations are confronted with strong spatial differences in their development and application. Against this background, the growing literature on the geography of innovation-based transformative change particularly emphasises the importance of regional specificities emanating mainly from institutions, technologies and actors.While many studies have explored eco-innovations’ enabling and constraining conditions at the regional level, scholarly debates lack insights into the extent to which eco-innovation activities in regions are carried out by incumbents or start-ups. Put differently, little is known about regional specialisations, i.e. regional comparative advantages, with regard to these two types of eco-innovation actors. This dissertation therefore sets out to gain a regionally nuanced understanding of the contribution of incumbents and start-ups to eco-innovation activities and its development over time. To ensure a broad and comparative perspective on green regional development, this research focuses on both sector-specific and general eco-innovation activities in German regions.By systematically reviewing the extensive yet fragmented body of research that revolves around the geography of eco-innovations, this dissertation first reveals complementarities that harbour promising avenues for future research. These conceptual elaborations are then followed by empirical investigations on regional eco-innovation specialisations using a novel data set on green patents and green start-ups. The findings suggest heterogeneous and persistent specialisation patterns of regions, while it is rather the exception that eco-innovation activities in regions are driven by both established actors and start-ups. In order to foster eco-innovations, a sustainability-oriented innovation policy should take greater account of the heterogeneity and path dependency of regional actor specialisations.