This study examined the effects of relational characteristics that managers of Korean firms operating in China have established with headquarters managers, managers of important local firms, and key local government officials on knowledge acquisition and performance through the internal and external networks of overseas subsidiaries. The results of this study showed that trust and communication frequency between headquarters and subsidiary managers had a positive effect on the subsidiary's acquisition of knowledge accumulated at headquarters. Meanwhile, trust between overseas subsidiary managers and managers of important local firms had a positive effect on acquiring local business knowledge, but informal networks did not have a significant effect. Conversely, however, informal networks with key local government officials were found to have a positive effect on acquiring local institutional knowledge. Furthermore, knowledge acquired from headquarters and local business knowledge had a significant effect on overseas subsidiary performance, but local institutional knowledge did not have a direct effect. However, local institutional knowledge had a positive effect on overseas subsidiary performance when combined with knowledge acquired from headquarters, playing a complementary role with headquarters knowledge, while local business knowledge had a negative effect on performance when combined with knowledge acquired from headquarters, suggesting that it is very difficult to achieve balance between knowledge that is similar in nature.