This paper analyses the impact of relational capital and relationship networks on business internationalisation, in particular in the technology sector in relation to internationalised Andalusian university spin-offs. First, a literature review based on these theories is carried out, from which a series of hypotheses are established in a pioneering way. These allow us to design a model of relationships that is empirically tested through a quantitative analysis. The study constructs were measured using five-point Likert scales. Once the data had been collected through the survey developed, they were coded for statistical analysis using the SPSS Statistics V28.0 programme. It is shown that the output of the international activity of these companies depends on their capacity to develop and sustain relationships with each of the different actors involved. Along this line, university spin-offs obtain diverse and strategically valuable external information and resources, significantly reducing business failure chances. The elements that influence the internationalisation process of the companies under study are relationships with customers, allies/collaborators, suppliers, and the company’s reputation and image. Similarly, those referring to relations with competitors, public bodies, and organisations have less impact. Nevertheless, it is evident that companies need to commit more time and resources to create, maintain, and develop relationships with different actors. Therefore, a strategic tool focused on international management is provided, based on the relationships of the spin-offs studied, which may constitute a starting point for its applicability to other industrial sectors and geographical areas.