A highly promising flower-shaped WS₂-WO₃/poly-2-aminobenzene-1-thiol (P2ABT) nanocomposite was successfully synthesized via a reaction involving 2-aminobenzene-1-thiol, Na₂WO₄, and K₂S₂O₈ as oxidants. The WS₂-WO₃/P2ABT nanocomposite demonstrated remarkable potential as a sensor for detecting harmful Hg²⁺ ions in aqueous solutions. The sensing behavior was evaluated over a wide concentration range, from 10⁻⁶ to 10⁻¹ M, using a simple potentiometric study on a two-electrode cell. The calibration curve yielded an excellent Nernstian slope of 33.0 mV decade⁻¹. To further validate the sensing capabilities, cyclic voltammetry was employed, and the results showed an increasing trend in the cyclic voltammetry curve as the Hg²⁺ concentration increased from 10⁻⁶ to 10⁻¹ M with an evaluated sensitivity of 2.4 μA M⁻¹. The WS₂-WO₃/P2ABT nanocomposite sensor exhibited exceptional selectivity for detecting Hg²⁺ ions, as no significant effects were observed from other interfering ions such as Zn²⁺, Ni²⁺, Ca²⁺, Mg²⁺, Al³⁺, and K⁺ ions in the cyclic voltammetry tests. Furthermore, the sensor was tested on a natural sample that was free of Hg²⁺ ions, and the cyclic voltammetry curves did not produce any characteristic peaks, confirming the sensor's specificity for Hg²⁺ detection. The sensor's cost-effectiveness and ease of fabrication present the potential for developing a simple and practical sensor for detecting highly poisonous ions in aqueous solutions.