<p>The inertial dynamics magnetization in superparamagnetic nanoparticles with biaxial anisotropy, particularly nutation resonance, is explored both theoretically and computationally. Using the inertial formalism rationalized by Landau-Lifshitz-Gilbert, we derive analytical expressions for the nutation resonance frequencies and linewidths, which are then validated through numerical simulations. The study examines magnetization response under microwave excitation, focusing on resonance characteristics such as frequency and linewidth. The analysis highlights how damping, anisotropy, and external fields influence nutation behavior, showing a non-linear dependence of linewidth on damping and field strength. Our results reveal that the inertial effects play a significant role at higher frequencies, causing the effective Gilbert damping coefficient to deviate notably from the original values suggesting the necessity of incorporating inertial terms to accurately describe the damping dynamics in high-frequency magnetization precession. Interestingly, higher values of original Gilbert damping coefficient lead to broader nutation linewidth of superparamagnetic nanoparticles, indicating faster relaxation and reduced coherence of the magnetization. For higher magnetic fields the linewidth becomes larger, indicating that the precessional frequency of the magnetization increases with the field strength, which in turn broadens the resonance. This behavior suggests that higher magnetic fields result in stronger magnetization dynamics but also to higher energy dissipation, thus affecting the precision of magnetic oscillations. Moreover, our simulations underline the complex interplay between torque-driven rotation and inertial effects, highlighting the weaker contribution of nutation compared to precession. The obtained results shed light on the inertial effects by elucidating the variation of the effective Gilbert damping coefficient as a function of the characteristic frequency, on the precession and nutation effects by illustrating the dynamic behavior of magnetization under the influence of external forces, on the nutation linewidth of superparamagnetic nanoparticles and on the complex susceptibility as a function of frequency of an external oscillating magnetic field. Altogether, these results may pave the way to advancing ultrafast magnetism and optimizing high-speed spintronic applications. Furthermore, our results highlight the critical role of inertial effects and the biaxial anisotropy, contributing to the development of more precise nanomagnetic systems and enhancing applications such as magnetic resonance imaging contrast agents and high-precision sensors.</p>