Knowledge transfer (KT) is considered one of the main determinants of business performance, innovation capacity and sustainable competitive advantages generation. But this requires the use of collaborative networks that provide access to valuable knowledge. The study of this phenomenon has not often been analyzed from an inter-organizational perspective due to the complexity of knowledge measurement. Although these concepts have been studied during the last decades, it is just in the last years that academia has put the focus on the issue. However, the multiple perspectives from which the phenomenon has been addressed, has generated the need to deepen the debate with the aim of systematically exploring the research scenario. Therefore, we first systematize previous literature that examines the link between KT and networks, and secondly, we explore the European collaborative ecosystem that drives innovation in SMEs. To achieve the first objective, we develop a systematic review of the literature following the PRISMA method allowing us to synthesize 190 high impact papers and to create a future research agenda of interest to the scientific community. For the second objective, complex network methodologies and centrality indicators are applied in order to identify the main drivers of European innovation in SMEs and to provide a picture of the current collaborative landscape among European countries.