Lanthanide-based metal–organic frameworks (Ln-MOFs) have emerged as one of the most promising classes of luminescent materials owing to their unique optical properties, structural versatility and exceptional sensing capabilities. Their characteristic sharp emission bands, long luminescence lifetime and high photostability make them suitable candidates for applications in chemical sensing, environmental monitoring, biomedical diagnostics and bioimaging. The luminescent behaviour of Ln-MOFs is significantly influenced by the nature of the organic ligands used in their construction. Functional groups such as amino (–NH₂), hydroxyl (–OH), nitro (–NO₂), carboxyl (–COOH) and halogen substituents modify the electronic environment of the framework, thereby affecting energy transfer efficiency, emission intensity, response time and detection sensitivity. 

This review critically examines the influence of ligand functionalization on the luminescent sensing performance of lanthanide-based MOFs. Recent research studies published during the last decade are comparatively analysed to understand how different ligand substituents affect sensing efficiency towards metal ions, antibiotics, biomolecules and environmental pollutants. The review also highlights the role of Eu³⁺- and Tb³⁺-based MOFs in fluorescence sensing, bioimaging and bioluminescence-inspired biosensing applications. Furthermore, a comparative assessment of response time, detection limit, luminescence intensity, fluorescence lifetime and selectivity is presented through tables and graphical analysis. Finally, the current challenges, recent advancements and future prospects of ligand-engineered Ln-MOFs are discussed. This review aims to provide a comprehensive understanding of structure–property relationships in lanthanidebased MOFs and to guide the rational design of next-generation luminescent sensing materials.