Smart luminescent materials derived from rare-earth complexes can dynamically respond to external stimuli and exhibit a tunable emission. The performance of these materials hinges on precise control of their molecular structures. This perspective establishes a direct roadmap from precision synthesis to function regulation. We systematically discuss how ligand design, supramolecular assembly, and nanomaterial integration serve as key strategies to regulate their luminescence and unlock multifunctions. Furthermore, we critically review recent advancements in translating these smart materials into applications, such as next-generation optoelectronics, sensing, information security, and biomedicine. Finally, future challenges and opportunities in this field are outlined to guide further development.