This paper reports the morphology, ion impact, and kinetic parameters of Y2O3:Dy3+ phosphor induced by 150-MeV Ni7+, 120-MeV Ag9+, and 110-MeV Au8+ swift heavy ions (SHIs) in the fluence range 1 × 1011–1 × 1013 ions cm−2. The X-ray diffraction (XRD), transmission electron microscope (TEM), and Fourier transform infrared (FTIR) studies confirm the loss of crystallinity of ion-irradiated phosphors. Thermoluminescence (TL) glow curves of ion-irradiated phosphors show a small shift in the position of peaks, along with an increase in intensity with ion fluence. Stopping and range of ions in matter (SRIM) calculations were performed in order to correlate the change in TL properties of ion-irradiated Y2O3:Dy3+ phosphors. The ion impact parameters show that the defect created by 110-MeV Au8+ ions is greater in number. Kinetic parameters were calculated from TL data using a computerized glow-curve deconvolution (CGCD) method.