Crystal facet engineering is proven to improve charge transfer of semiconductors. However, the facet-dependent properties and potential mechanisms of CeO₂ for surface-enhanced Raman scattering (SERS) performance have not been explored. SERS effect is a surface sensitive technology, so it is very important to study the relationship between semiconductor surface topography and SERS activity. Here, we synthesized CeO₂ (J2) with co-exposed {100} and {111} facet junction to effectively promote charge transfer (CT) between CeO₂ (J2) substrate and methylene blue (MB), so that the SERS activity is significantly enhanced compared to CeO₂ with only one exposed facets, which had a higher SERS activity with an enhancement factor (EF) of 3.77 × 10⁶. The phenomenon is due to that the facet junction of CeO₂ (J2) can promote electron-hole (e^--h⁺) separation under light irradiation for more efficient CT. In addition, the oxygen vacancies enriched in CeO₂ (J2) can provide an extra charge transfer path, which also facilitates the enhancement of SERS activity. Furthermore, the CeO₂ (J2) with excellent SERS activity was used to detect ATP with a detection limit of 6.90 nM. This work provides a new SERS platform and opens up a perspective for preparation of SERS semiconductor substrates.