Although the migration studies literature often takes social networks for granted, these social ties are not spontaneous but require effort and nurturing. There has been insufficient research on the actual process of networking, especially among highly skilled migrants. Our understanding of why and how migrants form networks with particular characteristics is still poor. In this article, we argue that it is necessary to consider both the structure and content of networks – the nature of the relationships as well as the flow of resources within various social ties. Drawing on qualitative data from a study of highly skilled French migrants in London's business and financial sector, we use a microanalysis of network‐making processes. In the context of London as a dynamic and highly competitive financial centre, we examine the importance of opportunities, skills and shared interests in building new social relationships from scratch. In addition, we also assess how mobility and proximity, virtual communication and co‐presence impact on geographically dispersed networks and why some long distance relationships endure while others fade over time. By bringing together classic literature on professional networking and wider discussions on how relationships are managed across time and space, our work contributes to a fuller understanding of why and how highly skilled migrants form networks with particular characteristics.