The widespread emergence of digital firms has important implications for international business theory. In this paper, we argue that because of systematic cross-industry differences in the local ecosystems digital firms need to develop in foreign markets, they will face differential costs and challenges of what we term liability of ecosystem integration (LoEI). The nature of the LoEI differs from both traditional concepts of the liability of foreignness (LoF) and the liability of outsidership (LoO). Rather than reflecting the need to overcome economic or psychic distance by learning about the host country (as with LoF) or investing in relationship-specific knowledge (as with LoO), overcoming LoEI requires investments in catalysing the co-development of a local ecosystem involving users, complementors and institutional actors specific to each business. We show how the level of LoEI a firm faces depends on the characteristics of its industry and its business model along three dimensions: the level of integration with local users, complementors, and institutions. These characteristics impact both firm's success in internationalisation and the level of concentration in the global market.