A novel blue-emitting phosphor Gd_4.67Si₃O₁₃:Bi³⁺ has been synthesized by a conventional high-temperature solid-state method. X-ray diffraction, and photoluminescence spectra were used to characterize the as-synthesized phosphor. Upon 370 nm excitation, the Gd_4.67Si₃O₁₃:Bi³⁺ phosphor exhibits a broad emission band centered at 455 nm. Monitoring the 455 nm emission, the Gd_4.67Si₃O₁₃:Bi³⁺ phosphor shows an intense broad absorption band ranging from 200 to 400 nm. The energy transfer mechanism between Bi³⁺ ions has been discussed, which is demonstrated to be dipole–dipole interaction. The critical concentration is 3 mol% and the critical distance is found to be 25.7 Å. The thermal stability and the CIE coordinates are also investigated in this work. The CIE coordinates of the Gd_4.67Si₃O₁₃:Bi³⁺ phosphor upon 370 nm excitation are (0.141, 0.096). All the results indicate that the blue-emitting phosphor Gd_4.67Si₃O₁₃:Bi³⁺ has potential applications for white LEDs.