Milnacipran (MCP) is a serotonin-norepinephrine reuptake inhibitor drug which is commonly prescribed for treating major depressive disorder and fibromyalgia. While electrochemical sensors play a crucial role in pharmaceutical and biomedical analysis, there is currently no sensor available for determining MCP. The present work illustrates the creation of an innovative electrochemical sensor for MCP and its integration in developing a square wave voltammetric (SWV) methodology for determining MCP in pharmaceutical and biological samples. Uranine (URN)-functionalized zeolitic imidazolate framework‑8 (ZIF-8) nanocomposites were obtained by one-pot synthesis and fabricated by controlled encapsulation on a carbon paste electrode. The materials and methodology used for fabrication of the sensor (URN@ZIF-8/CPE) were chosen due to their unique structural and analytical sensing performance characteristics. The interaction mechanism of URN@ZIF-8 was investigated and confirmed by spectroscopic techniques, computational analysis, and X-ray diffractometry. The encapsulation of URN within the microporous framework of ZIF-8 has been thoroughly investigated and the results revealed that this interaction occurs without the formation of covalent or coordination bonds; instead, it is primarily driven by electrostatic attraction and size complementarity within the ZIF-8 β-cage. The sensor (URN@ZIF-8/CPE) was fully characterized demonstrating uniform morphology, large specific surface area, and exceptional electrocatalytic performance to MCP. The optimum performance of the sensor was refined, analytical procedure of SWV was established and validated according to the analytical method validation guidelines. The linear range was 1.7 – 21.7 nM, with detection and quantification limits of 0.35 and 1.07 nM, correspondingly. The accuracy and precision of SWV procedure were confirmed as the recovery values ranged from 99.28 to 101.79 %, and the relative standard deviation values were ≤ 2.32 %. The established SWV approach was successfully applied to the quantitation of MCP in commercial tablets, plasma, and urine samples. The designed SWV methodology is the first electrochemical method for assessment of MCP in tablets and biological fluids. The importance of the method sits in its potential to provide a rapid, cost-effective, and reliable tool for quality control of MCP formulations and its therapeutic drug monitoring, which are crucial for ensuring optimum dosing and patient safety. Furthermore, the efficient integration of URN with ZIF-8 opens new avenues for the progress of advanced electrochemical probes for sensing of other biomolecules.