High-quality ZnSe:Eu, Mn quantum dots (QDs) with white light emitting were synthesized via a green preparation method in an aqueous solution using thioglycolic acid as a stabilizing agent. The composition of the QDs could be flexibly controlled by varying the amount of Eu or Mn cation. The effects of reflux time and Eu2+ ion dopant concentration on the luminescence properties were systematically investigated. The obtained QDs were characterized by photoluminescence spectrometry, X-ray powder diffraction, and high-resolution transmission electron microscopy. The proposed method formed cubic ZnSe:Mn2+, Eu2+ QDs with the maximum emission peak at 460 and 580 nm. In the optimal condition, the quantum yields of ZnSe:Mn2+, Eu2+ QDs could reach 27.68%. The CIE color coordinates were (0.328, 0.334), which agreed with those of pure white light (0.33, 0.33). The results verified that the ZnSe:Mn2+, Eu2+ QDs exhibited potential in light-emitting diode applications.