This work presents the synthesis of functional fluorescent latexes and their subsequent application in producing advanced fluorescent filaments for the additive manufacturing of smart and visually responsive objects. The fluorescent latex particles were obtained through a controlled emulsion polymerization involving methyl methacrylate (MMA), 2-hydroxyethyl methacrylate (HEMA), ethylene glycol dimethacrylate (EGDMA), and acrylamide (AAm), with sodium dodecyl sulfate, sodium bicarbonate, and triton X-100 as stabilizers, and potassium persulfate as the free-radical initiator under an inert argon atmosphere. Functionalization of the latex was achieved by incorporating 2,5-bis(5-tert-butyl-2-benzoxazolyl) thiophene (BBT) at 5 wt% of the polymer solids, providing strong optical emission psropertie. FTIR spectroscopy confirmed the presence of characteristic ester and amide functionalities, while dynamic light scattering (DLS) analysis revealed a mean particle diameter of 156.9 nm with a polydispersity index (PDI) of 0.27, indicating a narrow size distribution. The BBT-latex displayed intense green fluorescence in dark environments and was directly blended with polylactic acid (PLA) without dilution to produce composite fluorescent filaments via extrusion. These filaments not only exhibited enhanced fluorescence but also demonstrated improved mechanical strength compared to pure PLA. The 3D printing tests yielded objects that appeared white under daylight yet emitted vivid green luminescence under dark conditions. This study demonstrates the potential of BBT-latex/PLA composites as multifunctional materials for fabricating 3D-printed structures that combine aesthetic, optical, and structural functionalities, opening new opportunities for smart product design.