Based on first-principles calculations, the geometric, electronic, and magnetic properties as well as the relative stability of the fully hydrogenated and semihydrogenated AlN nanosheets (NSs) have been investigated. The results show that different with the bare graphite-like AlN NSs terminating with polar (0001) surfaces, the hydrogenated configurations preserve the initial wurtzite structure. Depending on surface hydrogenation and the thickness of AlN NSs, three magnetic configurations, that is, semiconductor, half metal, and metal states, are all observed. Analysis of formation energies indicates that, for the configuration n = 1, the hydrogen atoms adsorb on the top of Al sites is the most stable structure, while for the other configurations (n > 2), AlN-nH structure is more favorable energetically. The results indicated that hydrogenation on different Al and N sites might be an efficient route to tune their electronic and magnetic properties to realize potential applications in the fields of electronics and spintronics.