The interaction of intense laser pulses with magnetized relativistic hot plasma is critical to high-energy-density physics, yet temperature effects on fundamental processes require further exploration. This paper elucidates the resonant absorption of right-hand circularly polarized laser pulses in such plasmas via particle-in-cell simulations. We report a critical temperature-driven transition in the resonance character. In a non-relativistic hot plasma, absorption exhibits a sharp resonance at a wavelength uniquely determined by the background magnetic field. In stark contrast, for a relativistic hot plasma with electrons obeying a Maxwell–Jüttner distribution, we observe significant spectral broadening of the resonance. This broadening is attributed to the spread of electron cyclotron frequencies arising from the distribution of relativistic factors within the electron population. The absorption strength at a given wavelength correlates directly with the number of electrons satisfying the local resonance condition. This broadening mechanism provides a diagnostic reference for analyzing relativistic hot plasma states in astrophysical settings and intense laser-target interactions.