<p>The detection of organic pollutants at ultra-low concentrations is crucial for environmental monitoring, yet existing surface-enhanced Raman scattering (SERS) platforms often suffer from limited sensitivity, poor stability, and inconsistent signal reproducibility. To address these challenges, this study presents a high-performance SERS platform based on in situ gold (Au) nanoparticle-engineered Ti₃C₂T_x MXenes. This novel approach enhances signal amplification and ensures long-term stability for pollutant detection. The platform achieves an exceptional limit of detection (LOD) of 10⁻¹¹ M with an enhancement factor of 10¹⁰ for Methylene Blue (MB), demonstrating its superior sensitivity. Additionally, signal repeatability has been validated by calculating the relative standard deviation (RSD), and the SERS substrate retains 83% of its signal intensity after 5 months of storage, confirming its durability. Furthermore, the platform effectively detects polybrominated diphenyl ether (BDE-47), a persistent organic pollutant, at concentrations below the regulatory threshold of 10⁻⁶ M. These results highlight the potential of the proposed SERS platform for reliable and long-term environmental monitoring of hazardous substances.</p> Graphical Abstract <p></p>