Research on research and development (R&D) internationalization appears in several disciplines, with significant contributions in innovation, international business, management, and strategy research. Although the phenomenon is widely used in both research and practice, the impact of this concept on innovation is still not clear due to the multi-disciplinary nature of this relationship. This research gap is the motivation for the present study. Through a systematic review of 42 articles on R&D internationalization appearing in publication outlets for more than two decades, this paper examines the impact of R&D internationalization on innovation within the firm's boundaries. Based on this analysis, we map extant literature on the topic and we present an integrative framework of this relationship for future scholars to further build on, and executives to be guided by.