This study explores diaspora knowledge networks (DKNs) that mobile academics form in the context of the ongoing internationalization of higher education and science in the countries of the Global North. The study focuses on Russian-speaking computer scientists (RCS), who migrated from countries of the former Soviet Union in 1990-2010s and work(ed) in the United Kingdom. It is based on the mixed methods approach combining quantitative analysis of publications (298 RCS) with social network analysis of co-authorship ties (214 RCS) and qualitative analysis of semi-structured interviews (53 RCS). I find that DKNs arise in response to the emerging hierarchies that privilege native-born academics, expatriate scholars from the Global North, but generate systemic disadvantages for migrant scientists from “third countries”. In these conditions DKNs function as both migrant (ethnic) and scientific collaboration networks and produce a range of important effects for their members, improving migration experience and outcome, enhancing career prospects and research activity. But as highly gendered and male-dominated networks, DKNs substantially affect the migration and career trajectory of male scholars, granting much fewer benefits to women. While internationalisation is assumed to foster cross-cultural engagement, cosmopolitan dispositions, my study shows that it also stimulates the revival of ethnonational affiliations, leading to multiplication of DKNs, playing a vital productive role in highly diverse academic communities. Contributing to brain drain scholarship, my thesis finds that DKNs may have detrimental consequences for the home countries, while generating multiple gains for the host countries, though it depends on the composition and structure of the network.