In this paper the Quasiparticle-Phonon Nuclear Model (QPNM), based on QRPA (Quasiparticle Random Phase Approximation) phonons, has been utilized to investigate spin polarization effects on the groundstate magnetic properties such as intrinsic magnetic moment (g
K) and effective spin gyromagnetic factor (g
seff.) of odd-mass deformed 165–179Hf isotopes with K > 1/2. Investigations of the spin polarization effects of the even core on the magnetic moments show that the spin gyromagnetic factors (g
s) of the nucleons in the nucleus differ noticeably from the corresponding values for free nucleons and that the spin-spin interactions play an important role in the re-normalization of g
s factors of the odd-mass 165–179Hf isotopes. In addition, some theoretical predictions are presented for the magnetic moments of 165Hf, 167Hf, and 169Hf, whose ground state magnetic moments haven’t been experimentally determined yet.