In the current work surface of a glassy carbon electrode (GCE) is purposely modified with a suitable modifier to enhance its sensing characteristics. A composite of surfactant 1-(2, 4-initrophenyl)-dodecanoylthiourea (DAN) and gold nanoparticles (AuNPs) was employed as modified for the sensitive detection of oxoplatin (OXP), an extensively used anticancer drug. It enters into water bodies through improper handling in underdeveloped countries where drug disposal precautions are not fully respected. The designed platform (DAN/AuNPs/GCE) displays remarkable sensitivity 6.35 μA nM−1 and senses OXP with LOD of 14.5 pM under optimized conditions. The sensor was characterized by electrochemical techniques mainly cyclic voltammetry, electrochemical impedance spectroscopy, and square wave voltammetry. The response of OXP was also examined in the artificial serum sample. The modified electrode was found to have extraordinary discrimination ability for the selected drug even in the presence of a 100-fold higher concentration of several interfering agents and displayed remarkable repeatability and reproducibility with RSD up to 3%. The role of the electrode modifier in enhancing the concentration of OXP near the transducer surface and consequently intensifying the oxidation signal of OXP was validated from experimental and computational studies.