In this study, high-performance surface-enhanced Raman scattering (SERS) substrates and photocatalysts based on TiO₂ nanorod (TNR) arrays co-sensitized with black phosphorus (BP) nanosheets and Ag nanoparticles were successfully synthesized. The detection limit of the organic pollutant rhodamine 6G (R6G) on this novel SERS substrate was as low as 1.0 × 10⁻¹⁴ M. The calculated enhancement factor (EF) was as high as 3.81 × 10⁵. These results prove the excellent SERS sensitivity of the BP/Ag/TNR substrate. Furthermore, a good uniformity of the signals was observed during the detection process. The relative standard deviation of the intensity of the Raman fingerprint peak of R6G at 1650 cm⁻¹ was only 8.41%. Moreover, the BP/Ag/TNR substrate exhibited self-cleaning abilities through the photocatalytic degradation of the adsorbed R6G molecules. The BP/Ag/TNR substrate exhibited a maximum rate of 93.5% for the photocatalytic degradation of R6G. The corresponding photodegradation rate constant was 34.2 × 10⁻³ min⁻¹, which was approximately 3.98 and 2.01 times higher than those of the TNR and Ag/TNR arrays. The improved SERS performance and excellent photocatalytic activity of the BP/Ag/TNR substrate was due to the formation of high-density hot spots, expansion of the optical capture abilities, and enhancement of the charge transfer properties.