ABSTRACT Dendritic cells (DCs) are professional antigen‐presenting cells (APCs) that play a central role in regulating immune responses by linking innate and adaptive immunity. In recent decades, substantial progress has been made in understanding the development, classification, and diverse functions of DCs. However, a comprehensive overview integrating recent advances in the biology and therapeutic targeting of DCs remains lacking. This review systematically summarizes the origin, developmental pathways, and subset heterogeneity of DCs, including classical type 1 and 2 DCs, plasmacytoid DCs, monocyte‐derived DCs, and Langerhans cells. Moreover, it further details the core biological functions of DCs, including antigen capture, migration, and maturation; antigen presentation; activation of adaptive immunity; induction of immune tolerance; and modulation of innate immune responses. The pathological roles of DCs in diseases such as cancer, diabetes, and infectious diseases are discussed, highlighting emerging DC‐based therapeutic strategies. Importantly, this review provides a summary of both preclinical studies and clinical trials involving DC‐targeted therapies, offering a translational perspective. This work aims to deepen the understanding of DC immunobiology and to provide a valuable foundation for the development of novel DC‐based immunotherapies.