Neurotransmitters have been of immense scientific interest due to their importance as human-health biomarkers. Several reports suggest necessary improvisations in the sensing capabilities of these neurotransmitters. Herein, the authors report a novel synthesis methodology for bimetallic aluminum-tungsten (Al-W) nanosheets, with the hybrid nanostructure showing high specificity toward serotonin neurotransmitters. The inspiration to design hybrid metallic nanosheets depends on the inherited optical properties of the parent precursors. The interstate conversion (ISC) between Al-W nanosheets promoted photoluminescent behavior with serotonin. The PL study shows that serotonin drastically enhanced λem at 335 nm. The importance of emission below the visible spectrum is to modulate any possible aggregation-induced emissions, which earlier troubled analytical chemists. The understanding of the selective detection of serotonin from a group of similar neurotransmitters is discussed with nanomolar quantification. The quantified detection limit using Al-W nanosheets is 0.05 nm with high linearity (R2 = 0.9906). Furthermore, real-world quantification studies have been performed on human urine and serum samples with R2 of 0.9938 and 0.9801, respectively.