This article examines the mediating impact of open technology strategies (OTS) on the link between three types of external knowledge sources (i.e., scientific, institutional, and indirect partners) and business performance (BP). Structural equation modeling is conducted in order to test the research model based on a survey of 241 companies drawn from the database of Turkey's largest 500 manufacturing companies. The study's findings indicate that the implementation of OTS mediates the relationships between external knowledge sourcing (EKS) from scientific partners and indirect partners with BP. However, no support is found for the mediation effect of OTS on the link between EKS from institutional partners and BP. This article extends the innovation literature by empirically investigating open innovation in large-scale companies in emerging country settings.