This chapter examines the integration of two significant technological developments: the ‘Human Digital Twins’ (HDT) and blockchain technology, focusing on their applications and implications for digital identity and privacy management. HDTs represent an advanced form of digital replicas that encapsulate an individual’s physical, behavioural and psychological characteristics when using multimodal and multisource data. Their implementation promises to revolutionise interaction with the digital world, offering benefits in sectors as varied as personalised medicine and digital identity management. On the other hand, the blockchain provides a decentralised and secure platform for data management, offering robust solutions to the persistent challenges of privacy and security in a digitally connected world. The convergence of HDT with blockchain technology has the potential to enhance the security and privacy of personal data and radically transform existing methodologies in identity verification, system interoperability and personal data management within regulatory frameworks. This analysis is further explored by exploring HDT’s architecture, the challenges inherent in its implementation, and the unique opportunities it offers for advanced identity and privacy management. In addition, case studies are discussed, and future trends and emerging challenges in this dynamic field are outlined.