An alternative and convenient strategy for preparing carbon dots (CDs) with multicolor and dual-emission fluorescence is described. For this dual-emission characteristic, the short-wavelength emission reveals unique excitation-dependent fluorescence behavior, during which the long-wavelength emission remains unshifted regardless of the excitation. Consequently, such excitation-dependent ratiometric dual emission can be applied into a fluorescent tint control of this material between the cold and warm white-light regions. This unique property allows the CDs to be further translated into film sheets for visual detection of the irradiation source, and to also be conjugated with calf thymus DNA for multichannel bioimaging. These results offer new insights for the development of easy-to-handle techniques for material luminescent color tuning.