We augment the standard model gauge groups by an additional U(1)_X group with the corresponding gauge boson, Z', in the context of the type-I seesaw. After breaking U(1)_X by vacuum expectation values of scalar fields carrying even charges, the lightest of particles which is one of the heavy neutrinos, with odd U(1)_X charge is a dark matter candidate. We first find the minimum anomaly-free particle content and then discuss the light neutrino mass spectrum and mixing matrix, which consists of radiative corrections and tree-level contributions from the right-handed neutrinos.
Second, we demonstrate in certain simplified case, the required neutrino mass matrix to reproduce the oscillation observables can be easily achieved in this framework. Finally, we investigate the interplay between the DM relic abundance and lepton flavor violation.