The near-infrared light source possesses strong penetration, non-destructive testing capabilities, and a high signal-to-noise ratio for biological tissues. It finds extensive applications in component detection, security monitoring, biomedicine, national defense, and the military industry. However, the lack of highly efficient and portable near-infrared light sources has become a key obstacle to the development of intelligent detection technology. In comparison with traditional near-infrared light sources, phosphor-converted near-infrared LED light sources (NIR pc-LEDs) offer advantages such as portability and high efficiency. This study focuses on synthesizing Li₃Na₃Ga₂F₁₂∶Cr³⁺ broadband phosphors through a simple and environmentally friendly hydrothermal synthesis method. By controlling factors like holding temperature and holding time, an optimal synthesis scheme for fluorescent materials is determined. The influence of fluoride particle size, morphology evolution, and Cr³⁺ doping concentration on the luminescence properties of Li₃Na₃Ga₂F₁₂∶Cr³⁺ is also investigated. The synthesized Li₃Na₃Ga₂F₁₂∶Cr³⁺ material exhibits broadband emission ranging from 630 nm to 980 nm with a full width at half maximum (FWHM) of 110 nm and a peak value at 766 nm. Its internal quantum efficiency reaches an impressive 74%. Through successful packaging with commercial blue LED, a NIR wideband LED source is achieved. The output power of NIR light at 50 mA driving current is 10.32 mW, and the photoelectric conversion efficiency reaches 5.1%. Finally, the feasibility of using the NIR broadband LED light source in imaging fields such as medical and food detection is verified by NIR imaging of veins under chicken breast and night vision imaging demonstrations.