Yolk-shell (YS) Fe₃O₄@void@CeO₂ was alkaline-etched from Fe₃O₄@SiO₂@CeO₂ and applied as a magnetically recyclable SERS substrate. Using methylene blue (MB) as the analyte model, high SERS sensitivity was revealed with an enhanced factor of 1.1×10⁴. The enhanced light-scattering ability of the YS structure plays a vital role in the high SERS activity. Moreover, the improved molecule adsorption benefitting from the more exposed surface partly contributes to the improved Raman signal. The composite can be conveniently recycled through magnetic separation and light irradiation due to the photocatalytic degradation of MB molecules by CeO₂.