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Sensitive detection and efficient inactivation of pathogenic bacteria are crucial for halting the spread and reproduction of foodborne pathogenic bacteria. Herein, a novel Apt-modified PDMS-ZnO/Ag multifunctional biosensor has been developed for high-sensitivity surface-enhanced Raman scattering (SERS) detection along with photocatalytic sterilization towards Salmonella typhimurium (<i>S. typhimurium</i>). The distribution of the electric field in PDMS-ZnO/Ag with different Ag sputtering times was analyzed using a finite-difference time-domain (FDTD) algorithm. Due to the combined effect of electromagnetic enhancement and chemical enhancement, PDMS-ZnO/Ag exhibited outstanding SERS sensitivity. The limit of detection (LOD) for 4-MBA on the optimal SERS substrate (PZA-40) could be as little as 10⁻⁹ M. After PZA-40 was modified with the aptamer, the LOD of the PZA-40-Apt biosensor for detecting <i>S. typhimurium</i> was only 10 cfu/mL. Additionally, the PZA-40-Apt biosensor could effectively inactivate <i>S. typhimurium</i> under visible light irradiation within 10 min, with a bacterial lethality rate (L_b) of up to 97%. In particular, the PZA-40-Apt biosensor could identify <i>S. typhimurium</i> in food samples in addition to having minimal cytotoxicity and powerful biocompatibility. This work provides a multifunctional nanoplatform with broad prospects for selective SERS detection and photocatalytic sterilization of pathogenic bacteria.