Organic pollutants in dyed wastewater are hazardous to human health and the environment. The photocatalytic degradation of pollutants is considered a green treatment with significant social and environmental benefits. In this study, hollow BiOCl/TiO2 nanotubes with open pores at both ends, prepared by hydrothermal synthesis, were modified using phosphoric acid to promote photoelectron transfer. The hollow nanotubes offer an increased number of electroactive sites, which enhances the photoelectric transfer efficiency and reduces the electron-hole recombination rate. The modification by H3PO4 significantly optimized the photocatalytic activity of the nanotubes. The results show that the H3PO4 modified hollow BiOCl/TiO2 (molar ratio of BiOCl to TiO2 is 0.8) nanotubes exhibited the most efficient photocatalytic performance toward rhodamine B (RhB) with a photodegradation efficiency of up to 98.8% under visible-light illumination. These nanotubes have broad application prospects for the effective removal of organic pollutants from wastewater and can potentially inform future research on photocatalysts.