Photoluminescence originated from doped activators in the solid state materials usually faces the challenge of concentration quenching, restricting the further increase of photoluminescence intensity. Herein, a new strategy is demonstrated by the heavy doping Mn2+ into MgAl2O4, leading to the broad‐band near‐infrared (NIR) emission peaking at ≈825 nm with a full width at half maximum of ≈125 nm, as well as high internal quantum efficiency of ≈53% upon 450 nm laser excitation. Density functional theory calculation and extend X‐ray absorption fine structure provide a understanding of Al3+/Mn2+ disorder and Mn2+–Mn2+ aggregation in spinel Mg1–xAl2O4:xMn2+ with high Mn2+ content, which enables the formation of superexchange coupled IVMn2+–VIMn2+ pair. The NIR light‐emitting diodes fabricated by the 450 nm blue chip and Mg0.50Al2O4:0.50Mn2+ phosphor gives a high NIR output power of ≈78.41 mW under a driven current of 120 mA, and night‐vision application as light source in the dark is demonstrated. This work opens new paths for rational design of efficient broad‐band NIR emitting phosphor, and also provides new insights into the Mn2+ luminescence and the applications. A new strategy via Mn2+–Mn2+ aggregation is demonstrated by heavy doping Mn2+ into spinel MgAl2O4, enabling the formation of broad‐band near‐infrared (NIR) emission peaking at ≈825 nm with an FWHM of ≈125 nm. The NIR light‐emitting diode fabricated by this phosphor and 450 nm blue chip generates an NIR output power of ≈78.41 mW, showing high potential for night‐vision application.