A novel near-infrared (NIR) emitting ZnB2O4:Bi3+, Er3+ phosphor has been synthesized using a conventional solid-state reaction method. The X-ray diffraction, Photoluminescence (PL) properties, and PL decay curves of the samples were investigated thoroughly to have an insight into its luminescence performance. The XRD analysis reveals that an increase in annealing time results in the formation of single-phase for the as-prepared ZnB2O4 phosphor. The ZnB2O4:Bi3+, Er3+ phosphor show broadband Bi3+ emission at 428 nm along with an intense characteristic Er3+ NIR emission at 1535 nm under 335 nm excitation. The energy transfer (ET) from Bi3+ to Er3+ ions has also been discussed in detail. The detailed investigations carried out in the present work demonstrate that the incorporation of Bi3+ enhances the NIR emission intensity of Er3+ at 1535 nm by about 12 times. The critical distances (Rc) between Bi3+ and Er3+ for ET in ZnB2O4 were calculated by concentration quenching and turned out to be around 16.42 Å. The result indicates that the Er3+ NIR emission can be effectively sensitized via Bi3+:1S0→3P1 transition in ZnB2O4 phosphor.