The growing interest in Cr3+-doped broadband infrared phosphors stems from their promising applications in various fields. However, achieving highly efficient broadband emission based on these materials remains a significant challenge. To address this issue, we proposed a cation co-substitution method to enhance the near-infrared (NIR) emission of Cr3+-doped phosphors while simultaneously broadening the full width at half maximum (FWHM) of their emission peaks, as demonstrated in the case of CaMgGe2O6:Cr3+. Through controlled co-substitution of Ca2+ and Mg2+ cations by Na+ and Sc3+ cations, we prepared (Ca, Mg)1-x(Na, Sc)xGe2O6:Cr3+ (CMSxG:Cr3+) using a solid reaction method. This approach aims to deliberately adjust the strength of the crystal field experienced by Cr3+ to regulate the luminescence performance of the corresponding phosphors. Indeed, we observed a red shift of the emission peak from 850 to 902 nm, with the FWHM extending from 163 to 198 nm, as the concentration of ‘Na+-Sc3+’ pair increased, which would benefit iris acquisition. Importantly, the external quantum yield did not deteriorate; instead, it was enhanced from 13.6 to 26.2 %. Finally, we fabricated a broadband near infrared phosphor converted light-emitting diodes (pc-LED) by integrating CMSxG:Cr3+ phosphors with commercial 460 nm LEDs. An infrared output power of 118.01 mW at 300.00 mA was achieved with pc-LED based on Ca0.9Mg0.88(NaSc)0.1Ge2O6:0.02Cr3+ phosphor. Clear iris images acquired using these pc-LED as lighting sources demonstrate their potential applications in iris acquisition for biometrics.