Structural and electronic properties of armchair germanene nanoribbons functionalized by hydrogen atoms (H-AGeNR) are studied through density functional theory (DFT) method. The DFT quantities for analyzing the structural and electronic properties are fully developed through the DFT calculations, including the functionalization energy, relaxed geometric parameters, orbital- and atom-decomposed energy bands, electronic density of states, charge density, and charge density difference. Under hydrogen functionalization, the functionalization energy is achieved at -2.59 eV, and the structural parameters are slightly distorted. This provides evidence of good structural stability of the functionalized system. Besides, the very strong bonds of H-Ge are created because the electrons are transfered from Ge atoms to H adatoms, which induces hole density in the functionalized system, which is regarded as p-type doping. As a result, the π bonds of 4p_z orbitals at low-lying energy are fully terminated by the strong H-Ge covalent bonds, in which the strong hybridizations of H-1s and Ge-(4s, 4p_x, 4p_y, and 4p_z) orbitals have occurred at deep valence band. The termination of π bonds leads to the opened energy gap of 2.01 eV in the H-functionalized system that belongs to the p-type semiconductor. The enriched properties of the H-functionalized system identify that the H-functionalized system...