Three-dimensional (3D)-printed microneedles have emerged as powerful tools for diagnostic and biomedical applications due to their minimally invasive penetrability nature and compatibility with advanced sensing technologies. This chapter discusses recent developments in biosensing microneedle systems designed for multiplexed biomarker detection, continuous physiological monitoring, and disease diagnosis in the early age. Applications in point-of-care and home-based diagnostics are discussed, highlighting the potential of microneedle patches to allow rapid, user-friendly, and decentralized health monitoring. The chapter further examines the integration of 3D-printed microneedles with wearable devices and Internet of Things (IoT) platforms, enabling real-time health data transmission and advanced data analysis supported by artificial intelligence. Key challenges, including data reliability, device integration, and scalability, are also addressed, along with future directions for the development of intelligent microneedle-based diagnostic systems. Overall, this chapter underscores the growing role of 3D-printed microneedles in next-generation personalized and digital healthcare.