A metal–semiconductor heterojunction material was synthesized by electrodepositing Au nanoparticles onto the surface of WO₃ nanoflowers that were grown on TiO₂ nanotubes and applied, for the first time, to the surface-enhanced Raman scattering (SERS) detection of dyes. Owing to their nanoflower structure, a localized surface plasmon resonance was generated on the surface of the Au/WO₃/TiO₂ nanosheets, which brings about multiple enhanced three-dimensional electromagnetic fields. An enhanced factor of 3.6 × 10⁶ was achieved. The spot-to-spot change in the SERS intensity was less than 15% and the SERS substrate could be preserved for at least 50 days. The analysis of dyes in real samples provided a recovery rate of 94.33–115.6%, indicating its potential applications in environmental analysis.