The present work suggests the use of an economic, ultra-sensitive, and sustainable electrochemical sensor based on the electropolymerization of DL-methionine as a conducting polymeric film on a gold nanoparticle-modified battery graphite electrode, poly(DL-met)/AuNPs-BGE, for the analysis of vincamine (VIN), a natural alkaloid spasmolytic drug used for managing Alzheimer's, neurodegenerative, and normal aging-related cognitive diseases. The sensor exhibited a broad linear working range from 0.003 to 100 µM (R2 = 0.9985), with a low detection limit of 0.00046 µM, and considerable repeatability and reproducibility results. The presented approach was applied effectively for VIN quantification in the pharmaceutical dosage formulation, spiked human urine, and plasma samples with good recovery ranges of 95.78–101.20% and low RSD values of 1.51–1.62% (n = 3), showing the suggested sensor's reliability and efficiency for selective analysis of VIN in various matrices. Additionally, the sustainability of the method was verified utilizing different analytical greenness metrics, in addition to the very recent blue applicability grade index (BAGI).