Although Small-to-Medium-sized-Enterprises (SMEs) frequently make vital contributions to both national and global economics and innovations, the relative influences of Open Innovation (OI) on SME performance is inconsistently argued in the literature. This study is set to fill this gap through an investigation of the details and dynamics of SMEs’ engagement in OI. Further, its impact on performance, through the perspective of knowledge networking, is examined. Specifically, this study investigates the relationships between OI activities, reverse-knowledge sharing, stakeholder relationship and SMEs performance in a context of numerous Vietnamese industries. Results revealed that OI activities are statistically insignificant when related to SMEs’ overall performance. However, it should be noted that OI indirectly affects SME performance through the mediation effect of reverse-knowledge sharing and the moderation effect of stakeholder relations. Practical implications and theoretical potential for future research are discussed.