Internationalization and academic entrepreneurship have been receiving a lot of attention not only in academic research but also in policy practice. While academic spin-offs suffer from limited resources and lack of entrepreneurial skills, they often penetrate international market through their innovative products and technology since the very early years of their establishment. In the literature, little attention has been paid to explicitly examine the internationalization process of academic spin-offs as well as the role of non-academics. In order to investigate the impact of non-academics on the performance of spin-offs, we carried out an empirical analysis of 126 Spanish spin-offs which were divided into two market categories, international and domestic market. With regard to the percentage of non-academics in founding team, we found that their impact was more relevant to the performance goals than to innovativeness. On the other hand, the size of non-academic networks contributed significantly not only to the performance goals but also to innovation. However, we did not find a significant relationship between the strength of non-academic networks and the performance goals and innovativeness of the international spin-offs. Overall, we concluded that the role of non-academics was crucial for supporting the internationalization of the spin-offs.