<p>The Ni²⁺ ion has garnered increasing attention due to its broadband emission in the near infrared (NIR) II region (1000–1700 nm). However, it exhibits low light absorption efficiency and cannot be effectively excited by blue light chips, thereby significantly impeding its commercial application. Herein, we introduced the Cr³⁺ sensitizer ion into MgGa₂O₄:0.01Ni²⁺, which remarkably enhanced the absorption efficiency of blue light and improved the photoluminescence properties. It is noteworthy that the MgGa₂O₄:0.24Cr³⁺,0.01Ni²⁺,2 wt% H₃BO₃ sample exhibits a broadband emission spanning from 1000 to 1600 nm, with an emission peak at 1290 nm, achieving high internal and external photoluminescence quantum yields of 81.91% and 62.51%, respectively. The occupancy of Cr³⁺ ions at the lattice sites in MgGa₂O₄ was comprehensively discussed and analyzed using various optical characterization techniques. Additionally, based on X-ray absorption near-edge structure spectra and low-temperature photoluminescence spectra, it has been determined that the energy level of Cr³⁺ in tetrahedral sites acts as an intermediate level for energy transfer from Cr³⁺ to Ni²⁺, leading to high energy transfer efficiency. The electro-optical conversion efficiency of the packaged NIR phosphor-converted light-emitting diode device reaches 11.38% under a driven current of 20 mA, and the NIR output power can reach up to 52.66 mW at 350 mA, showcasing the exceptional electro-optical properties of the as-fabricated NIR pc-LED within the NIR II range.</p>