In this work, a facile green synthesis using Oxalis corniculata leaf extract (OCLE) as a biodegradable reducing and capping/stabilizing agent was carried out for the construction of Oxalis corniculata leaf extract–derived silver nanoparticles (OCLE-AgNPs). Moreover, OCLE-AgNPΔGO nanocomposites were fashioned simply by mixing a GO suspension and supernatant OCLE-AgNPs via a one-pot environmentally benign method. The AgNPΔGO nanocomposites are biocompatible materials for potential applications such as antibacterial activities against two different types of bacterial cells, namely Gram-positive Bacillus subtilis and Gram-negative Escherichia coli and selective electrochemical sensing to itraconazole (ITRA) at the fabricated GCE (AgNPΔGO@GCE). AgNPΔGO@GCE sensors gave excellent outcomes for ITRA as higher current response over the bare GCE. Under optimized conditions, the oxidation peak current of ITRA varied linearly with a wide range of the concentration between 26.7 μM and 103.8 μM with a correlation coefficient of 0.997 and a detection limit of 0.1276 μM, for differential pulse anodic stripping voltammetric (DP-ASV) technique. In addition, the possible mechanism for the ITRA oxidation was further verified and explained by single-electron transfer (SET) and proton removal mechanism steps. The developed sensor exhibited good repeatability, reproducibility, and stability. The use of environmentally benign and renewable plant material offers enormous benefits of eco-friendliness applicability.