The objectives of this research were to analyze: (1) the effect of knowledge sharing on business performance of Small and Medium Enterprises (SMEs), (2) the effect of product innovation on business performance of SMEs, and (3) the effect of knowledge sharing on business performance of SMEs moderated by product innovation. Samples of the research consisted of 80 SMEs in East Java, Indonesia. Path Analysis was used to test the proposed hypothesis. Results showed that: (1) knowledge sharing has a positive and significant effect on business performance of SMEs, (2) product innovation has a positive and significant effect on business performance of SMEs, and (3) knowledge sharing has a positive and significant effect on business performance of SMEs moderated by product innovation.