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Excitation-dependent photoluminescence is most frequently encountered in quantum dot systems and organic-inorganic metal halide hybrids. Here, we report a new paradigm for excitation-dependent luminescence by grafting picolinic acid (pa) onto the single-crystalline nanosheets of RE(OH) 2.94 (NO 3) 0.06 · n H 2 O (RE = Y/Tb, Y/Eu, Y/Tb/Eu). Grafting of pa through an interaction between COO− group of pa and RE3+ ions on the surface of nanosheets, did not change the morphology and the crystal structure of the original nanosheets, and the grafting content of pa reached the maximum value at R = 0.25 (R , the molar ratio of pa to nanosheets). Effective intramolecular energy transfer from coordinated ligands to the activated RE3+ ions, called the antenna effect, can give rise to an enhanced photoluminescence upon light irradiation. In this work, multi-modal energy transfer of pa → Eu3+, pa → Tb3+ → Eu3+, and the reconstructed Tb3+ → Eu3+ resulted from the antenna effect of pa contributed to the excitation-dependent luminescence behavior and greatly enhanced emission intensity. The luminescence reversibly undergoes repeated cycles by switching the excitation wavelength, indicating the grafted nanosheets are the potential materials of switched "on/off" optical sensors. The use of the energy transfer to the activated RE3+ ions through the antenna effect recommends a new paradigm for luminescence improvement and excitation-dependent luminescence. Unlabelled Image • Picolinic acid (pa) was grafted onto the rare earth hydroxynitrate nanosheets. • Grafting of pa did not change the morphology and the crystal structure. • The antenna effect of pa leaded to dramatically enhanced and excitation-dependent luminescence. • The grafted nanosheets are the potential materials of switched "on/off" optical sensors. [ABSTRACT FROM AUTHOR]