As the strategic importance of knowledge that resides in host county nationals (HCNs) increases, this study begins with the motivation to advance our understanding of HCNs’ cultural intelligence (CQ) as a prominent promoter of their knowledge sharing. Drawing on social identity theory, we hypothesized a serial mediation effect of (i) relationship between HCNs and expatriates, and (ii) HCNs’ organizational identification. We empirically tested the model with 414 responses collected by HCNs working for 16 foreign subsidiaries in Korea. Results from structural equation model show that high CQ of HCNs is positively related to the relationship between expatriates and HCNs. This positive relationship between two parties is found to facilitate organizational identification of HCNs. Lastly, it was shown that HCNs’ organizational identification has a positive impact on their active knowledge sharing within foreign subsidiaries. Moreover, we found that the impact of HCNs’ CQ on their knowledge sharing is fully mediated by two suggested mediators. This research contributes to investigating the role of CQ in knowledge management from the perspective of HCNs, rather than following extant studies that give more focus on expatriates. We also proposed the full mediation model that identifies the process by which HCNs’ knowledge sharing is promoted in a multicultural work environment.