Crystals are materials in which atoms, ions, or molecules are arranged in a periodic and ordered three-dimensional structure. Among novel crystalline nanomaterials, self-assembled DNA crystals form via the base-pair complementarity of DNA molecules. Unlike traditional ionic or metallic crystals, self-assembled DNA crystals offer high programmability, enabling the design of addressable frameworks with tunable pore sizes for host-guest interactions and further functionalization through interfacial chemical modifications. Over the past 15 years, research interest in DNA nanotechnology and DNA self-assembled nanomaterials has surged. This review provides a comprehensive overview of the design principles, regulation, and functionalization of self-assembled DNA crystals for applications in molecular recognition, catalysis, and photonic crystals, while also addressing their emerging challenges within the broader context of nucleic acid chemistry and structural DNA nanotechnology.