Purpose: Currently, lifelong learning and sustainable employability are increasingly fostered in the context of interorganizational networks, which provide workers with access to network activities (e.g., training, career counseling). This study aims to investigate the relationship between workers' participation in network activities and their sustainable employability by considering workers' experiences with the network activities. This study also examines the role of relational factors, including network trust and leader-member exchange, as conditions that may influence the link between workers' participation in network activities and their sustainable employability (i.e. workability, perceived employability and vitality). Design/methodology/approach: This study has a mixed methods design. A quantitative approach (cross-sectional, questionnaire) was used to establish associations between variables. This approach was supplemented with qualitative data (semistructured interviews) to explore whether Self-Determination Theory can provide an explanation for the associations and the role of (relational) factors that workers perceive as hindering or facilitating in that process. Findings: The results suggest that participating in network activities have promising benefits for both workers and organizations by facilitating the work ability and perceived employability components of sustainable employability. For these relationships, workers' satisfaction of their need for competency and relatedness serves as explanatory mechanisms. Moreover, the actualization of benefits of network activities is influenced by relational factors both within the network (i.e. trust) and within organizations (i.e. leader-member exchange). Originality/value: This study investigates workers' experiences with network activities, regarding fostering workers' sustainable employability, and the role of relational factors. Specifically, it considers Human Resource Management practices from a network-level perspective, which is currently understudied. By doing so, this study adds a unique perspective to the Human Resource Management, sustainable employability and career literature streams.