Three series of new ultraviolet-emitting Ca9Y(PO 4)7:Ln3+ (Ln = Ce, Gd, Pr) phosphors were synthesized, and their luminescence was investigated. Under vacuum ultraviolet excitation Ca9Y(PO4)7:Ce3+ phosphors emit UVA light with one broad emission centered at 346 nm, on account of the 5d1 → 4f1 transition of Ce3+ ions; the optimal doping concentration of these phosphors is 0.2 mol. Ca 9Y(PO4)7:Gd3+ phosphors show a strong 4f7 → 4f7 transition and a sharp UVB emission band at 312 nm; the optimal doping concentration of these phosphors is 0.7 mol. The PL spectra of Ca9Y(PO4)7:Pr3+ show two broad UVC emission bands centered between 230 and 340 nm, owing to the 4f15d1 → 4f2 transition of Pr3+ ions; the optimal doping concentration of these phosphors is 0.2 mol. Under 172 nm excitation, we found that the luminescence intensity of the UVA-emitting Ca9Y(PO4)7:0.2Ce3+ is 0.3675 times that of BaSi2O5:0.05Pb2+, that of the UVB-emitting Ca9Y(PO4)7:0.7Gd3+ is 1.7 times that of YAl3(BO3)4:0.25Gd 3+, and that of the UVC-emitting Ca9Y(PO4) 7:0.2Pr3+ is 1.5 times that of LaPO4:0.1Pr 3+. The thermal stability investigation indicated that the luminescence decay was only 9.2%, 18.2%, and 10.3% for Ca9Y(PO 4)7:0.2Ce3+, Ca9Y(PO 4)7:0.7Gd3+, and Ca9Y(PO 4)7:0.2Pr3+ at 250 °C relative to that at ambient temperature, respectively. The Ca9Y(PO4) 7:Ln3+ (Ln = Ce, Gd, Pr) phosphors exhibit high emission efficiency and excellent thermal stability.