Although adopting human resource management (HRM) practices has been shown to be positively related to intellectual capital, onboarding and organizational socialization have not been discussed as potential drivers of intellectual capital. The Socialization Resource Theory shows how personal, relational, and structural resources influence newcomer adjustment, which is linked with various outcomes like organizational commitment, intention to quit, turnover, and job performance. Therefore, the purpose of this chapter is to describe organizational socialization as an essential factor in building and retaining intellectual capital. During socialization, human capital can be developed through training, skill development, and newcomer learning. Successful newcomer adjustment helps to preserve intellectual capital because it decreases intention to quit and, thus, retains valuable and knowledgeable employees. Through organizational socialization, newcomers acquire relational resources that might enhance organizations’ relational capital. Finally, a structured onboarding process can be an integral part of an organization’s organizational capital that helps to codify knowledge. In essence, onboarding is instrumental in managing, developing, and leveraging the human capital that forms a significant part of intellectual capital. The novelty of this article is to connect intellectual capital and organizational socialization in a comprehensive model. The effective implementation of onboarding measures can enhance organizational performance, innovation, and long-term sustainability. The chapter also explores the potential benefits of virtual and digital onboarding in adapting practices to individual newcomer needs. The overarching focus is on human capital, digitization, and performance.