Microneedles (MNs) represent a groundbreaking technology at the intersection of medicine and cosmetics, providing innovative, minimally invasive solutions for drug and nutrient delivery. This chapter examines MNs systems, detailing their mechanisms of skin penetration and comparing passive and active delivery strategies. We discuss their wide-ranging applications in medicine, including vaccine administration, pain management, and chronic disease treatment, as well as their cosmetic uses for anti-ageing, skin hydration, and rejuvenation therapies. A focus on clinical efficacy and safety is provided, supported by a synthesis of key studies and an overview of existing regulatory standards. Additionally, the chapter addresses the current challenges hindering widespread adoption and identifies future directions for MNs innovation and market expansion. By integrating current knowledge with an outlook on forthcoming advancements, this chapter aims to deepen the understanding of MNs as a versatile platform for the safe, effective delivery of therapeutic and cosmetic agents, fostering new avenues for clinical and commercial applications.