This paper reports a quasilinear hydrazone-based mononuclear dysprosium(III) compound, namely, {Dy(Hppyh)₂(SCN)₃}·2MeOH (I), where Hppyh is pyrazine-2-carboxylic acid pyridin-2-ylmethylene-hydrazide. Compound I behaves as a single-ion magnet (SIM) based on the optimal dc field application of 0.7 kOe, showing a complex magnetic relaxation phenomenon with a tunneling relaxation time of 6.1 ± 0.3 × 10⁻³ s and an effective spin reversal barrier of 22.6 ± 1.1 K for the low- and high-frequency regions, respectively. More importantly, detailed comparative experimental and theoretical investigations reveal that the complex magnetic relaxation was most likely associated with the single Dy^III ion behavior as well as the short-range intermolecular magnetic dipolar interactions.