The BiOBr:Yb3+,Er3+/g-C3N4 (BYE/CN) p-n junction photocatalysts were successfully fabricated by a stepwise method. Experimental results show that Er3+/Yb3+ were successfully doped into BiOBr lattice. As-obtained BYE/CN exhibited strong NIR light absorption and upconversion emission from NIR to UV-visible due to the upconversion transition of Er3+. The p-n junction was constructed due to the appropriate alignment band structure of BYE and g-C3N4, which distinctly suppresses the recombination rate of electron-hole pairs. Compared with pure BYE and CN, as-synthesized BYE/CN samples exhibit distinctly improved photoactivities under the irradiation of visible or NIR light, which can be attributed to the upconversion effect of Er3+ and the construction of p-n junction. This result may provides a promising system for efficient harvest of the NIR light, which will contribute to the utilization of solar energy in the future.