The utilization of nanomaterials (NMs) to produce nanosensors for detecting drugs in a wide range of materials has attracted global attention. Various categories of NMs have been synthesized and applied for the qualitative determination of some additives, contaminants, and illicit materials owing to their unique physicochemical properties at the nanoscale to impact desired effects. Rapid and facile detection techniques employed for on-site analysis of illicit drugs using NMs are reviewed. It is noted that NMs are good candidates in the fabrication of nanosensors for the sensitive detections and determinations of illicit drugs. Thus, this review is focused on the application of these sensors for illicit drug detection. Hence, the application of plasmonic/optical properties of NMs to enhance illicit drug detection in biological samples has been discussed. The fabricated sensors have been shown to possess enhanced selectivity, sensitivity, cost-effectiveness as well as improved automation. As highlighted in the in-depth review, the sensors are designed to utilize biological receptors with a transducer component to detect the analyte-biorecognition element interaction which resulted in producing an optimum signal.