Abstract Y2O3:Eu3+ hexagonal microprisms with uniform morphology and size were successfully prepared on a large scale via a fast microwave-assisted method followed by a subsequent heat treatment. X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and fluorescence spectrometer were used to characterize the samples. SEM results show that these microprisms have an average length of about 4 μm and diameter of about 1.6 μm. Furthermore, the ends of the microprisms are rough. The Y2O3:Eu3+ hexagonal microprisms show a strong red emission with the most strongest peak centering at 610 nm under ultraviolet excitation (394 nm). The formation mechanism for the microprisms was briefly discussed.