PurposeElectronic commerce (EC) strategy – performance logic has gained significant popularity in the literature, particularly from the resource-based view (RBV) of theoretical underpinning. However, such an obsession of focusing on organizations' complementary resources has been increasingly challenged, which has pressed the RBV to examine the possibility of external factors that can also impact firm performance. In this study, the authors shed light on the firm's external readiness—defined as the extent to which a firm's customers and suppliers perceive EC as important—in the relationship between SME's complementary resources and firm performance.Design/methodology/approach The authors employed a refined data set based on the British EC Award database, in which the authors sampled 430 British SMEs' senior managements and examined how EC investments made by the SMEs influenced firm performance, and how their external readiness moderated this main relationship.FindingsThe results showed that, in line with the RBV perspective, SMEs' complementary business resources and human resources both had strong and direct impacts on the firm performance. They were also strongly mediated by EC functionality. In addition, SMEs' external readiness moderated the relationship between human resources and firm performance and that of EC functionality on firm performance.Originality/value The findings contribute to RBV theory building by extending earlier research on the role of technology as performance enablers for SMEs and shed light on the often-overlooked role of SMEs' external readiness.