Neurodegenerative diseases, such as Parkinson’s and Alzheimer’s diseases, affect the elderly worldwide and will become more prevalent as the global population ages. Neuroinflammation is a common characteristic of neurodegenerative diseases. By regulating the phenotypes of microglia, it is possible to suppress neuroinflammation and, in turn, help prevent neurodegenerative diseases. We report a noninvasive photonic approach to regulating microglia from overexcited M1/M2 to the resting M0 phenotype using a special near-infrared (NIR) light emitted by the SrGa₁₂O₁₉ : Cr^{3 +} phosphor. The absorbance and internal and external quantum efficiencies of the optimal Sr ( Ga_0.99Cr_0.01)12O₁₉ phosphor synthesized at 1400°C for 8 h using 1 % H₃BO₃ + 1 % AlF₃ as flux are 53.9 % , 99.2 % , and 53.5 % ; the output power and energy-conversion efficiency of the LED device packaged using the optimal SrGa₁₂O₁₉ : Cr^{3 +} phosphor driven at 20 mA reach unprecedentedly 19.69 mW and 37.58 % , respectively. The broadband emission of the NIR LED device covers the absorption peaks of cytochrome c oxidase well, and the NIR light can efficiently promote the proliferation of microglia, produce adenosine triphosphate (ATP), reverse overexcitation, alleviate and inhibit inflammation, and improve cell survival rate and activity, showing great prospects for photomedicine application.