Non‐cytotoxic and green‐emitting fluorescent hydrogels were constructed from a cellulose solution containing Ba2MgSi2O7:Eu2+ green phosphor in a NaOH/urea aqueous system. The structure, optical properties and cytotoxicity of these hydrogels were studied. The Ba2MgSi2O7:Eu2+ phosphor particles were dispersed evenly in the cellulose hydrogel matrix. Good luminescent properties of Ba2MgSi2O7:Eu2+ phosphor were maintained in the hydrogels, leading to strong green emission under ultraviolet excitation. Fluorescent hydrogels have no obvious cytotoxicity in a 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) proliferation test, and have potential use in in vivo applications like optical imaging and drug delivery.