The rapid development of minimized near-infrared (NIR) phosphor-converted LEDs (pc-LEDs) has evoked a large demand for broadband NIR phosphors and will enable breakthrough NIR spectroscopy applications. Consequently, the search for NIR pc-LEDs which can emit in the NIR-II window (1000–1700 nm) has become increasingly urgent. Herein, an unprecedented long-wavelength NIR MgTi₂O₅:Ni²⁺ phosphor that exhibits broadband NIR emission covering 1200 to 1700 nm with a full width at half maximum (FWHM) of 245 nm is successfully synthesized. By combining the MgTi₂O₅:Ni²⁺ phosphor with an ultraviolet LED chip, a high-performance NIR pc-LED is fabricated, which has a NIR output power of 3.6 mW at 300 mA driving current. These results indicate that the fabricated NIR-II pc-LED device is a promising candidate as a broadband light source for NIR spectroscopy applications including night vision, high-penetrating imaging, and information restoration. For instance, the secret information covered by ink can be recovered with the aid of an NIR-II pc-LED. This work not only provides a new material that has great potential as a NIR light source, but also demonstrates a set of approaches to expand the application of NIR spectroscopy and imaging technology.