Industrial wastewater discharge from textile industries poses a significant threat to subsurface environmental quality, particularly in complex geological settings where contaminant migration is difficult to detect using surface observations alone. This study aims to delineate and characterize subsurface contamination associated with textile industrial waste in the Cikijing River, Bandung, Indonesia, with particular emphasis on its occurrence within a volcanic–structural geological environment. An integrated approach was employed by combining Electrical Resistivity Tomography (ERT) and physicochemical analyses. ERT surveys using a dipole–dipole configuration were conducted along four profiles, while sediment samples were analyzed for pH, Electrical Conductivity (EC), and Total Dissolved Solids (TDS) to validate geophysical interpretations. The inversion results reveal a stratified subsurface consisting of topsoil, clay, and dense sandy gravel layers. A prominent low-resistivity anomaly ranging from 2.63 to 9.82 Ωm was identified within the clay layer at depths of 0.5 to 4.3 m, extending laterally up to 22.5 m. This anomaly is interpreted as a contaminant plume resulting from the accumulation and retention of industrial effluents within low-permeability materials. Physicochemical measurements support this interpretation, showing acidic conditions (pH 5.4–5.7), elevated EC values reaching 2,710 µS/cm, and high TDS concentrations exceeding 1,999 ppm, all of which surpass WHO and national environmental standards. These findings confirm the significant impact of textile wastewater infiltration on subsurface conditions. Nevertheless, the results provide practical value for environmental assessment, pollution monitoring, and remediation planning in industrial regions. The originality of this research lies in integrating geophysical and physicochemical approaches to delineate contamination within a volcanically influenced and structurally controlled subsurface system, offering new insights into contaminant behavior in complex geological environments.