Production of novel organic semiconductor nanomaterials is essential for enabling the development of personal, portable and flexible electronic modules. This work presents Ni(II)-Schiff base complexes with enhanced Seebeck coefficient and weak ferromagnetic ordering for thermoelectric and magnetic devices. Four Ni(II)-Schiff base complexes (namely [Ni(CHN3O4Br)]2H2O, [Ni(CHN3O]2H2O, [Ni(CHN5O8Br)] and [Ni(CHN5O]H2O) have been synthesized in nanosized dimensions. The electrical and thermoelectric properties have been studied, and comprehensive discussions have been presented to understand the electrical conduction mechanisms. The electrical conductivity measurements reveal that the conduction is due to the charge carriers hoping between the atomic sites of the same energy levels in the molecule as well as the transfer of the charge carriers between the neighboring complex molecules due to overlapping of their orbitals. The thermoelectric measurement confirms that the nanocomplexes (NCs) are non-degenerate P-type semiconductors with enhanced Seebeck coefficient values compared with those reported for other organic materials. The NCs exhibit antiferromagnetic to paramagnetic transitions with the increase of temperature and weak ferromagnetic ordering at 300 K.