A series of CaWO4 :3Eu3+ :xBi3+ (x = 2, 5, 7 and 10 at.%) nanophosphors was prepared through the efficient low-temperature ethylene glycol route. Their structural, as well as photophysical, properties were studied. X-ray diffraction analysis and a X-ray photoelectron spectroscopy survey confirmed that the Bi3+ and Eu3+ ions incorporated perfectly into Ca2+ and without disturbing the lattice. The samples exhibited almost spherical morphology with average particle sizes from 10 to 30 nm. For the nanoparticles, Fourier transform infrared spectroscopy featured broad absorption bands around 871 and 778 cm-1 that were due to antisymmetric stretching, whereas a peak at 435 cm-1 was assigned to antisymmetric bending vibrations of the bonds in [WO4 2- ] clusters. The nanophosphors showed orange-red luminescence, which was further tuned to red by incorporation of sensitizer Bi3+ ions. This colour tuning of the nanoparticles is described in the context of energy transfer from the WO4 2- group to sensitizer Bi3+ and activator Eu3+ ions under 394 nm excitation. A CIE diagram supports this colour tunability.