A systematic theoretical study of the doping of Zn17 nanoparticle with 3d transition-metal (TM) impurities is presented. Calculations are conducted within the density functional framework as implemented in the VASP code at the generalized gradient approximation for the exchange and correlation effects. The ground state of Zn17 has been recently shown to be a dihedral superatom hollow cage in a singlet state [ Angew. Chem., Int. Ed. 2015, 54, 2111 ]. We show that, among the 3d elements, endohedral doping of a quasi-undeformed cage results favorable only for Cr and Cu, which as free atoms display a very stable (half-filled and fully occupied, respectively) d shell electron configuration. This structural configuration allows to maximize the spin magnetic moment of the chromium-doped cage. Co and Ni also adopt an endohedral configuration, but with a strong deformation of the cage and a rather compact structure due to the large electron hybridization between the TM states and those of the Zn host. Doping with the other TM impurities results in an exohedral arrangement, also concomitant with a marked electron hybridization. Most of the TM impurities retain a large part of the spin magnetic moment that they have in a vacuum due to localization of part of their 3d states. The Zn atomic environment is found to be spin-polarized and modulates the total spin moment of these molecular magnets depending on the induced moments and magnetic couplings. © 2015 American Chemical Society.