In recent times, drug-facilitated sexual assault has become more prevalent in sexual assault and abuse cases. Consequently, there is a growing emphasis on developing of Lab-on-a-Chip devices for on-site, visually accessible detection of date-rape drugs. This study presents the development of a portable microfluidic device for the naked-eye detection of benzodiazepines in adulterated beverages, one of the prevalent compounds implicated in drug-facilitated sexual assault cases. For the detection of benzodiazepines, Cobalt (II) thiocyanate complex was employed for the first time in a solid support. The structure of the microfluidic device comprised several layers, including a paper strip containing the reaction reagents, as well as several polymeric materials (hydrophilic pressure sensitive adhesive, double-sided pressure sensitive adhesive and poly(methyl methacrylate)). This integrated design rendered the device both autonomous and handheld, with the unique capability to load the sample automatically, unlike other devices that require manual sample loading. The benzodiazepines microfluidic device exhibited the capability to detect drugs across a diverse range of beverages and concentrations. The quantitative detection limit was calculated to be 0.15 mg mL-1 for diazepam and 0.11 mg mL-1 for midazolam, both of which are within the minimum effective dose range, making them useful devices in real scenarios. Overall, a microfluidic device with significant potential for industrialization and commercialization was successfully developed, offering a rapid, portable, and user-friendly solution for the on-site, naked-eye detection of diazepam and midazolam adulteration in real samples. Its autonomous operation, ease of use, and adaptability to various beverage matrices make it a promising tool for real-world applications.