Theorizing within the umbrella of evolutionary economic geography (EEG) has improved the understanding of how inter‐firm relatedness conditions knowledge spillovers, and how this affects the long‐term evolution of regions. Still, there are shortcomings in this approach associated with a quantitative and generic methodology, a static notion of relatedness, and a weakly developed policy and institutional perspective. In particular, there is a need for a better understanding of the mechanisms through which relatedness is developed and how policy affects existing and emerging relatedness. Certain mechanisms for knowledge transfer have been suggested, such as labour mobility, firm diversification, spin‐offs and social networks. But do the same mechanisms apply to all industries and in all territories, or are there specific mechanisms of knowledge sourcing at work in different contexts? To shed light on these questions, the article reports on a comparative case study of two knowledge‐intensive industries (life science and publishing) located in the Oslo metropolitan region. Based on a case study, the article suggests that both industries source knowledge through similar types of channels. However, despite similarities in how knowledge is accessed and absorbed in this diverse urban context, knowledge sourcing also seems to be conditioned by industry‐specific dynamics, policies and institutions.