Lanthanide metal complexes as novel luminescent metal-organic frameworks with potential application such as probes, sensors and labels, have greatly been developed. This paper presents novel nanocomposites by reacting terbium salt with the sodium carboxymethyl cellulose (NaCMC) at different pHs, Which were characterized by SEM, TEM, FTIR, XPS, WAXD, GPC, UV-Vis, and PL. The results show that Tb3+ ions react with O of COO-, -OH, and -COC on NaCMC. The morphologies of these nanocomposites showed spheroidal-like with the size around 100 nm at around neutral pH, but show rod-like and band-like around 100 nm in width and about 500 nm in length at pH = 11 and 12. They emit bright green characteristic fluorescence of Tb3+ under ultraviolet light due to the antenna effect when NaCMC transfer the energy efficiently to the Tb ions around neutral pHs. However, at higher pH, they show weaker fluorescence intensity in spite of strong crystalline because abundant Na+ are involved in them and affected the efficiency of energy transfer between NaCMC and Tb3+. These nanocomposites could find potential biological applications base on their fluorescent and biodegradable properties. POLYM. COMPOS., 38:E498–E507, 2017.