The introduction of multiple metal atoms into a single-phase structure is a highly desirable strategy to enhance the functional properties of materials. Herein, we report the synthesis of a high-entropy (Cu, Mn)(Co, Fe, Cr)₂O₄ oxide by simultaneously doped cations into the A and B sites of a spinel structure through a solid-phase synthesis method. Through comprehensive characterization of its microstructure and chemical composition, we confirm the successful formation of a single-phase high-entropy spinel structure. Remarkably, the as-synthesized material exhibits exceptional infrared radiative properties, with a high emissivity of 0.896 and 0.839 in the wavelength ranges of 0.78–2.5 μm and 2.5–16 μm, respectively. Furthermore, the material demonstrates excellent thermal stability, maintaining its high emissivity even after annealing at 1300 °C for 200 h, respectively. Importantly, the developed high-entropy oxide can be easily deposited on a variety of substrates, with superior radiative properties and excellent suitability. In particular, spraying on 304L SS sheets provides excellent heat transfer compared to bare leakage substrates, which display high infrared emissivity values of 0.958 (0.78–2.5 μm) and 0.865 (2.5–16 μm). Overall, this work provides a promising approach to developing potential infrared radiative materials with diverse potential applications, particularly in the field of high-temperature heat transfer.