We report morphological and ferromagnetic property control in ZnO nanorod structures by an optimum doping of Ni and Li. Nanostructures of Zn_0.97-xNi_0.03Li_xO (x = 0, 0.03, 0.05, 0.08, and 0.10) are prepared by a solvothermal method. High aspect ratio (5-15) ZnO nanorods transform to particles (with 1-3 aspect ratio) influenced by 3 at. % Ni substitution in ZnO (Zn_0.97Ni_0.03O). It is remarkable to note that the Zn_0.97Ni_0.03O particles completely retain the nanorod shape with significantly increased aspect ratio (15-30) when 3 at.% Li ions are codoped in Zn_0.97Ni_0.03O (Zn_0.94Li_0.03Ni_0.03O). Li substitution also enhances ferromagnetism with largest magnetization (0.8 emu·g^-1) observed for Zn_0.94Li_0.03Ni_0.03O. For Li concentration >3 at.%, the aspect ratio as well as the magnetization decreased considerably. These experimental observations are explained by first-principles modeling. At low Li-on-Zn acceptor concentrations, the total magnetization is increased by lower Ni d-state populations, whereas at higher Li concentrations the population of ZnO host states decreases the ferromagnetism by induced magnetic moments on the oxygens. We discuss the significant implications of these results on the nanorods structures of room temperature ferromagnetic materials, which are expected to play pivotal role in developing spintronic devices.