<p>Using a solid-state reaction method combined with elemental doping and microstructure engineering, Cupronickel_X/Co₄Sb₁₁.₅Te₀.₅ (x = 0.1, 0.3, 0.5, 0.7; x in wt%) skutterudite-type thermoelectric materials were rapidly synthesized at 923&#xa0;K within 45&#xa0;min. X-ray diffraction (XRD) analysis reveals that the primary phase of the samples is CoSb₃, accompanied by minor amounts of secondary phases, including Cu₂(Zn,Fe)SnS₄, Cu₇Te₄, and CuP₂. SEM and EDS analyses show significant grain refinement in the samples, with a maximum grain size ≤ 1&#xa0;μm and most grains in the nanometer range. Multiscale pores are formed at the grain boundaries, which are abundant, and the elemental distribution within the grains is relatively uniform. The synergistic doping strategy of cupronickel and Te increases the grain boundary density and interfacial complexity, thereby suppressing the lattice thermal conductivity of the samples. With increasing cupronickel doping concentration, a wider variety of heterogeneous phases precipitate, suppressing the effective electron concentration in the CoSb₃ matrix and thereby raising the electrical resistivity while enhancing the absolute Seebeck coefficient. Excessive doping, however, coarsens these secondary phases, reduces the number of grain boundaries and the density of scattering centers, ultimately elevating the lattice thermal conductivity. At 781&#xa0;K, the sample with x = 0.1 achieved the highest power factor (1769.46&#xa0;μW·m⁻¹·K⁻²), while the sample with x = 0.5 exhibited the lowest lattice thermal conductivity and total thermal conductivity (0.87 W·m⁻¹·K⁻¹ and 1.56 W·m⁻¹·K⁻¹, respectively). When x = 0.3, the sample achieved the maximum <i>zT</i> value of 0.79.</p>