This study conducted an integrated environmental risk assessment of benzene, toluene, ethylbenzene, and xylene (BTEX) alongside selected polycyclic aromatic hydrocarbons (PAHs) in water and sediment samples from the Bonny River, Nigeria, a region subject to intensive petroleum exploration and industrial discharge. Samples were collected from five strategically selected sites and analysed using Gas Chromatography–Mass Spectrometry following EPA protocols. Results showed peak BTEX concentrations at Site 4, with benzene reaching 92.0 µg/L in water and 328.7 µg/kg in sediment, while xylene reached 405.2 µg/kg in sediment. PAHs such as naphthalene and benzo[a]pyrene also peaked at Site 4, with concentrations indicative of ongoing hydrocarbon contamination. Physicochemical indicators including temperature, conductivity, and salinity showed spatial increases downstream, supporting anthropogenic impact. Ecological risk assessment revealed Risk Quotient (RQ) values above 1 for BTEX at all sites, with the highest ecological threat observed at Site 4. Human health risk evaluation based on Average Daily Intake (ADI), Hazard Quotient (HQ), and Lifetime Cancer Risk (LCR) identified significant non-carcinogenic and carcinogenic risks, particularly at Sites 3, 4, and 5, where HQ exceeded 1 and LCR for benzene and benzo[a]pyrene surpassed the USEPA acceptable threshold of 1×10⁻⁴. The study concludes that hydrocarbon contamination in the Bonny River presents a substantial ecological and public health concern, warranting immediate regulatory and remediation action supported by continuous environmental monitoring.