A reflector for a GaN-based light-emitting device, method for manufacturing the reflector and GaN-based light-emitting device including the reflector are provided. The reflector is formed on a p-type GaN-based epitaxial layer and includes: a whisker crystal of un-doped GaN, formed on a surface of the p-type GaN-based epitaxial layer with a predefined density distribution and at a position that corresponds to a dislocation defect of an epitaxial layer; and a metal reflective layer, formed on both the p-type GaN-based epitaxial layer and the whisker crystal. The whisker of un-doped GaN is positioned on the dislocation defect of the p-type GaN-based epitaxial layer, so that the Ag reflective layer can be separated from the dislocation defect of the p-type GaN-based epitaxial layer, thereby effectively preventing Ag from moving inside the dislocation defect via electromigration, and largely decreasing the possibility of current leakage of the light-emitting device including the Ag reflector.