Pharmaceutical residues in veterinary wastewater pose significant environmental risks due to their persistence, biological activity, and potential ecological impact. Common contaminants such as non-steroidal anti-inflammatory drugs (NSAIDs), sulfonamides, and estrogens are widely used in livestock farming and often bypass complete removal in wastewater treatment systems. Simultaneous detection of these compounds in complex matrices remains challenging, highlighting the need for rapid, selective, and eco-friendly monitoring methods. This study developed a novel magnetic solid phase extraction (MSPE) method using magnetic hydrophobic deep eutectic solvents (Fe₃O₄@HDES) for the simultaneous extraction of NSAIDs, sulfonamides, and estrogens from veterinary wastewater. Fe₃O₄ nanoparticles functionalized with a hydrophobic deep eutectic solvent improved affinity for analytes across different polarities. The optimized MSPE, coupled with high-performance liquid chromatography and diode-array detection (HPLC-DAD), achieved recoveries of 90.2 % to 112.7 % and low detection limits of 0.02 to 0.50 μg L⁻¹. The method is simple, rapid, and requires minimal organic solvent, making it ideal for routine monitoring. Sustainability assessment using ComplexGAPI and AGREEprep tools, confirmed strong alignment with green chemistry principles, while the BAGI index validated its analytical reliability for real environmental samples. This work demonstrates an efficient, selective, and green analytical platform for monitoring pharmaceutical contaminants in environmental waters. By integrating magnetic HDES-based extraction with HPLC-DAD, the method offers a sustainable solution for multi-class drug analysis. Its high performance, minimal environmental footprint, and compliance with green chemistry metrics position it as a promising approach for routine environmental surveillance of pharmaceutical residues.